I have a home built computer with Windows Vista operating system. I clicked on a link that infected my system with a Trojan, though I don't know which one.

When I open Internet Explorer, here is the "System Error!" I get:

"Your computer was infected by unknown trojan. It's dangerous for your system (critical files can be lost!) Click OK to download the antispyware program to clean your system! (Recommended)".

I have not clicked 'OK', I simply close the window, and Internet Explorer shuts down. I have scanned my computer with Ad-Aware 2007 and Symantec AntiVirus, but it is unable to remove anything. I have also tried to scan my computer with these programs with the system restore off, but it also did nothing. I also tried deleting my Java cache, but it did nothing, too.

*EDIT* 12:19am Monday, March 24 2008****
The trojan is affecting C:\Windows\ausctv32a.dll

I do not know what Trojan is on my computer, but I would appreciate any help and advice any of you have. Please respond soon. Thank you in advance!

Go to SAFE MODE with networking -- run a scan with these programs -- How To Get Into Safe Mode (http://www.computerhope.com/issues/chsafe.htm)

Online Scan
BitDefender Online Scanner - Free Online Virus Scan (http://www.bitdefender.com/scan8/ie.html)

Online Scan
The home of Spybot-S&D! (http://www.safer-networking.org/index2.html)

Online Scan
http://www.ewido.net/en/download/Also use this program to get rid of junk

Download CCleaner 2.05.555 - filehippo.com (http://www.filehippo.com/download_ccleaner/)

Download Latest Version Of Ccleaner and run it

I have been using AVG security AVG Anti-Virus and Internet Security - Real-time protection against viruses, spyware and malicious websites (http://www.grisoft.com/ww.homepage). I've had it a couple years now and all those spam pop-up are gone. I highly recommend this free program. I've tried some other ones and this is the best for me.

Run the anti spyware remove programs spybot Security News from the net: Spybot search and destroy spyware and popups (http://securitynewsfromthenet.blogspot.com/2007/03/spybot-search-and-destroy-spyware-and.html) and superantispyware Security News from the net: SUPERAntiSpyware Home Edition (free version) (http://securitynewsfromthenet.blogspot.com/2007/04/superantispyware-home-edition-free.html) to get rid of the nasties

Run a complete scan with free curing utility Dr.Web CureIt!
Dr.Web CureIt! – download free anti-virus! Cure viruses, Best free anti-virus scanner! (http://www.freedrweb.com/)

The best bullet proofed browser is
Firefox+Adblock Plus +noscript
Download and run Firefox to protect your from future spyware attacks and pop ups which are coming in through internet explorer (Trojan downloaders, win32 ) .Then update your windows through Firefox
Browser attacks aren't easy to spot because they piggyback on legitimate traffic that doesn't exhibit many obvious warning signs
Security News from the net: spyware fighter essentials (http://securitynewsfromthenet.blogspot.com/2007/05/spyware-fighter-essentials.html)
Install addition protection into Firefox with
Adblock Plus
Adblock Plus: Installation (http://adblockplus.org/en/installation)
There's a browser safer than Firefox...
... it is Firefox, with NoScript!
NoScript - JavaScript/Java/Flash blocker for a safer Firefox experience! - get it! - InformAction (http://noscript.net/getit)