Why does my computer suddenly freeze, and why does my taskbar and desktop icons disappear?

Recently I tried installing an Active X control on my pc in order to view on of those online video but when I installed it it turned out to be a virus (trojandownloader.agent). I ran various anti-virus software to try to remove it but none seem to work at removing the virus (norton, avast, trojan remover). Is the reason for my computer freezing due to the virus and what can I do to remove the virus and stop my taskbar and desktop icons from disappearing...Please help, its driving me crazy!!!

Why does my computer suddenly freeze, and why does my taskbar and desktop icons disappear?anti virus software

To clean up your virus/spyware problems

Update your anti-virus

Update your anti-spyware software.

http://www.microsoft.com/athome/security... [if you do not have one]

or

http://www.superantispyware.com/superant... [free home edition]

Restart your PC in safe mode

http://www.pchell.com/support/safemode.s...

And run a full scan with both.

You may also want to have a look at your start up items by using msconfig.

http://www.netsquirrel.com/msconfig/

Be careful with the items you uncheck, you can have a look here to see if they are necessary

http://www.greatis.com/appdata/index.htm...

You should also have a look at your IE Add-ons.

http://www.microsoft.com/windowsxp/using...

Disable any you do not use.

After you reboot back to normal mode, down load and install ccleaner to fix any registry problems.

http://www.ccleaner.com