Help! Avast did not found a terrible virus!

[Myldemon]

Sunday I had a very big problem on my PC (Win XP). I received a game from a 'friend'. I asked Avast to check it. It was OK. I executed it. I saw 'Secret Defense' and 'NASA'. I tried to stop it, but too late! It forced my computer to reboot. Then Avast and ZoneAlarm did not run. I tried to launch them, but it was impossible. I tried a system restauration. Impossible. I have a partition on my harddisk (C:and D:). I formatted C and re-install Win XP, Avast and ZoneAlarm. They run, but there are strange things. ZoneAlarm blocked intrusions. I cannot install Internet Explorer 7 and Win Live Messenger 2009. I'm afraid the virus is still there. I have a wireless network connection and my husband was also connected sunday. He has a notebook with Vista. Is it possible that he has also the virus? What can I do? Thank you very much and please excuse me for my poor english.

[Lisandro]

General cleaning procedure is:

1. Clean your temporary files.
2. Schedule a boot time scanning with avast with archive scanning turned on. If avast does not detect it, you can try DrWeb CureIT! instead.
3. Use SUPERantispyware, MBAM or Spyware Terminator to scan for spywares and trojans. If any infection is detected, better and safer is send the file to Quarantine than to simple delete them.
4. Test your machine with anti-rootkit applications. I suggest avast! antirootkit or Trend Micro RootkitBuster.
5. Make a HijackThis log to post here or this analysis site. Or even submit the RunScanner log to to on-line analysis.
6. Disable System Restore and then reenable it again.
7. Immunize your system with SpywareBlaster.
8. Check if you have insecure applications with Secunia Software Inspector.

Also, it would be useful a full computer on-line scanning:
Kaspersky
ESET NOD32
Trendmicro housecall
F-Secure
BitDefender

[Myldemon]

Thank you for your answer!
I think it was Conficker or something like that. I am using Microsoft Malicious Software Removal Tool on my PC and on the computer of my husband. If that doesn't work, I'll try HijackThis. Thank you again!