Use another antivirus software

I've always recommended InoculateIT to people until Chip magazine ranked it on 15th place (16 programs were tested). The optimal free/shareware choice right now would be AntiVir 6, you can get it at
free-av.com. First disk scan after install of AntiVir 6 yielded two (mostly harmless) trojans on my computer and it deleted them both. InoculateIT didn't report these trojans.
However, AntiVir didn't prevent RC5 trojan from being remotely installed on my (in that time) non-firewalled machine.