i think i'm in deep shit

i was in dreamviews chat when all slowed down and internet explorer (yeah i know i search my own trouble using it but that's what i have) freaked out.
so i terminated it, and then noticed that the zonealarm icon had an x. i disconnected from internet, opened zonealarm (complete suite) and it said that there was a system error and it had to be restarted. all the parts (antivirus, firewall ecc) were off.

then all of them came back alone to normal (looked as).

i made the complete scan and found nothing, but all the logs (firewall log, antivirus log ecc) were empty - they showed only the operations made after the moment of the crash. i lost months of logs, but that's not what worries me.

i would badly want to know which BIG EVIL virus or worse has done it and is lurking freely in my pc now, unseen and unfound.

i SO would like to get rid of it without having to reinstall everything - i don't even HAVE everything and i'm so sad...

sure, if my pc tomorrow won't restart, i'll have no way to read the replies