I had downloaded some codec a day or two ago, and ever since, my computer ( which has been running popup free for several months with Spyware Blaster, AdAware, and SpyBot as well as Mozilla Firefox) is rampant with popups and annoying messages.

Here is the first one :

System Warning:
    4 Errors Found
    -Your computer has slowed down
    -You get popups
    -Your homepage has changed
Click 'OK' to download spyware scan

If I click on it, it leads to a page opened with Internet Explorer.

I also get random IE5 popups leading right to spyware software pages such as Adaware Bazooka.

I even get a black '!' in a yellow triangle which sometiems flashes next to the time display in the lower right hand corner. Double click on that, and it leads right to another one of these pages.

What in the HELL is going on, and how do I stop it?

You've got some stubborn spyware. Download Microsoft Anti-Spyware Beta from Microsoft's site, restart in safe mode, run it, clean everything it shows up as Spyware.

also try BHOdemon

At this point, my advice to you is:

Format and reinstall Windows.

Then, get Spyware Search and Destroy, Crap Cleaner, MS Anti Spyware, a VERY GOOD Anti-virus (don't be afraid to pay), Kerio or McAfee Personal Firewall (some people dislike McAfee and Norton, but I've never had a problem with McAfee), etc. Install these before you download ANYTHING ELSE. Don't download attachments or programs from anything less than a completely reputable site.

Read the following thread: AnandTech Consolidated Security Thread. Follow its advice.

It can take as little as 15 minutes for a clean but unprotected computer to become infected to the point of a system crash on the internet.

ETA: NEVER NEVER NEVER click on a popup or ad that asks you to 'fix your computer' or install something. They are MALWARE. Bad, bad malware. Also, start using a browser like Firefox or Opera (I prefer Opera, but most people prefer Firefox), which will prevent some security flaws in IE (such as, in IE, things can be downloaded and installed without your knowledge).

Also, when you're not installing things, if you're running XP, you might try staying in a Limited user account rather than one with Administrator priveleges. This will help prevent installations.

And always update your anti-malware software. ALWAYS.

if adaware and spybot arent getting it, try running HijackThis! and look for anything that shouldnt be there.  Also MSCONFIG, and uncheck anything that shouldnt be starting up under the startup section.

DON'T reformat your computer at the first sign of trouble; if you always do that, you'll never know exactly what got you--and a lot of spyware and viruses can be safely removed! This is like having your car's engine rebuilt every time you need an oil change. Much of the time it really isn't necessary.
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First off, what codec did you download, and exactly where did you download it from? Did you google it with the word "spyware"?

If your PC runs really slow online, than you may need to disconnect it, and use another computer to look for info online.
~

Don't remember the exact codec, but once I found out it was trouble I deleted it.

UPDATE - I ran Microsoft's Anti-Spyware Beta 1, it did remove a whole lot of crap and detect a few changes IE5 tried to make, but it still has not taken care of the more annoying popups. SpyBot, Adaware and HijackThis all have failed too.

Do I have any other options besides reformatting the drive and reinstalling Windows XP?

Quoted: Quoted: System Warning:     4 Errors Found     -Your computer has slowed down     -You get popups     -Your homepage has changed Click 'OK' to download spyware scan Right here is where you fooked up even worse. You just invited even MORE spyware in! Do you have XP? Maybe you can go back to before you did this and restore.

Dude, chill. I never did click okay on those things.

How would I go back and restore things? Yes, I do have XP...

system restore in control panel

its a life saver

Since your homepage has been changed you probably have an "about:blank" virus.

They can be very difficult to get rid of, most anti-spy softwear won't remove them.

Listen to me carefully.

Geeks To Go

Go there.

Follow their advice.

Do what they say.

Stay off the p0rn sites.

Done!

Tagged for my new Dell...Another reason that I love my Mac....

Formatting windows is a last resort.  99.9% of spyware can be cleaned with "HijackThis".

Quoted: Formatting windows is a last resort.  99.9% of spyware can be cleaned with "HijackThis".

I think we have worse customers than you do.  With most of our customers, even a combination of HijackThis, Ad-Aware, Spybot S&D, and Giant anti-spyware (which is quickly getting much better because their programmers have access to information about backdoors in Windows that others do not have) will not usually fix the problems.   We're back to having to reformat and start over again about 90% of the time.  They also use Outhouse Express, so that's another source of the browser hijacks that are hard to clean-up.  It's getting to the point where even our most technically incompetent customers are asking us about Linux.  I just wish I had more time to switch them since it would save time in the long run.z

Quoted: Quoted: Formatting windows is a last resort.  99.9% of spyware can be cleaned with "HijackThis". I think we have worse customers than you do.  With most of our customers, even a combination of HijackThis, Ad-Aware, Spybot S&D, and Giant anti-spyware (which is quickly getting much better because their programmers have access to information about backdoors in Windows that others do not have) will not usually fix the problems.   We're back to having to reformat and start over again about 90% of the time.  They also use Outhouse Express, so that's another source of the browser hijacks that are hard to clean-up.  It's getting to the point where even our most technically incompetent customers are asking us about Linux.  I just wish I had more time to switch them since it would save time in the long run.z

+1 on zoom

I have spend hours on trying to fix computers with the exact same problem.   take the HD out scan it in another system.  run adaware, spybot, ewido. a squared, hijackthis, put the drive back into the machine run the scans on their HD.  and the computer is still havig issues.  

back up your data(if it isn't already)  and do a fresh install

adaware, spybot, and regular antivirus will never be able to keep up with the virus/trojans, spyware in the web right now.   until people learn how to follow basic surfing, email, file downloading rules.   its just a matter of time untill it happens again.   sorry to be so negative.   But i fight this stuff everyday, and i dont see it getting better

At this point, I think you're screwed. But one last thing to try before you reformat. Go over here and post your Hijack This log:   castlecops.com/forums.html

I've had some luck there. If they can't help you, a reformat/reinstall Windows is in your immediate future.

Also try the free trial version of TrojanHunter, available here for a 30-day demo... trojanhunter.com/

I used to work on people's computers for them. Nearly all had serious spy/malware/trojan issues. 75% of them, I ended up reformatting, because it would have taken far more time than it was worth. 6-8-10 hours of work to remove some stubborn stuff, or 4 hours for a reformat/reinstall OS/update OS.

Quoted: At this point, I think you're screwed. But one last thing to try before you reformat. Go over here and post your Hijack This log:   castlecops.com/forums.html I've had some luck there. If they can't help you, a reformat/reinstall Windows is in your immediate future.

y post it their.  their web page tells you what to remove

hijackthis.de

read and follow directions

Quoted: I had downloaded some codec a day or two ago, and ever since, my computer ( which has been running popup free for several months with Spyware Blaster, AdAware, and SpyBot as well as Mozilla Firefox) is rampant with popups and annoying messages.

Obviously you installed some codec loaded with all sorts of  spyware.  Next time download your codecs from Free Codecs so you don't have to go through this again.