my email account was used to send a virus

Viruses and worms
1

my hotmail account was used to send a virus attached to an email (‘happy day!.zip’, a Win32:Malware-gen)to everyone in my hotmail address book today while my pc was turned off. the microsoft malicious software removal tool and avast 5.0.677 full system scans now find no malware on my pc.what is my best course of action to prevent further spoof emails being sent under my email account name ?

2

Try changing email password(in case you didn’t already).

3

Besides changing your password, I suggest:

  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 MBAM (or SUPERantispyware or even Spyware Terminator) to scan for spywares and trojans. If any infection is detected, it is better and safer to send the infected file(s) to quarantine (Chest), rather than simply deleting 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. Clean your Hosts file (replacing it) with HostsMan tool.
  7. Disable System Restore and then reenable it again.
  8. Immunize your system with SpywareBlaster.
  9. Check if you have insecure applications with Secunia Software Inspector.