I wasn't able to tell from his post, but could he be talking about the fake anitvirus malware that calls itself "Windows XP Antivirus" or "Vista Antivirus" or something like that. These things trick lots of people because they look authentic. Your standard antivirus programs usually will not catch nor remove these. Often, this malware will disable your real antivirus...even in safe mode! These things are HARD to get rid. I often have to go into safe mode with networking then download and run smitfraudfix. Then afterwards, run my real anti-malware programs.
Mario, could this be what is happening?