Can't remove this Virus

I am running XP Pro and have recently had my system infected with what I believe is a Trojan, a friends PC also seems to be infected with a similar virus.
Both viruses have pretty similar characteristics. When I log on using the IE icon my homepage is reset to about:blank, and I receive a messenger warning advising that someone is trying to access my computer through port 245. The messenger refers to the virus as something like spssmydoom.cih (I can find out the proper name if need be).
Another problem is that loads of popups appear and when I attempt to access certain sites such as Yahoo Mail the page resets to about:blank and popups appear advising I have Spyware on my computer.
I have run Avast and Microsofts AntiSpyware and neither can find any viruses or infected Registry Keys, I have also run the Avast Virus cleaner which has not found any infected files.
Has anyone come across this virus and know how to correct it? I could really do with a step by step ‘idiots’ guide to removing it as have tried everything I can think of.
Cheers in advance.

What you have is called a Browser Hijacker.
Click on the link in my signature and follow the instructions in the malware removal section.

Thanks for the reply, I have carried out the following tasks:
I switched off system restore, rebooted in safe mode and ran the virus checker, 8 trojans were found but were not moved to the virus chest as there was an RPC(?) failure.
I have attempted to follow the links regarding host files and instructions relating to these but the virus opens up a search page titled ‘One More Search’ and get several popups titled ‘One Of The Best’.
Are there any other tasks that I can carry out to try and get rid of this virus?

With XP it is possible to schedule a boot-time scan from within avast.

http://img.photobucket.com/albums/v325/for-dwr/boottime.jpg

go to either pcworld.com or cnet.com and download the free helpers called BHODemon and CCleaner…i had the same thing and got rid of them after running those programs.