FBI emailed me

I woke up bright and early this morning at 8am (Class at 2pm Tues/Thurs)to resume my paper writing. Naturally, I checked mail before I did anything, and guess what? I have about 10 "junk" mails, two of which were from FBI/CIA of the United States informing me that I had gone to 30 illegal websites last night (while I was sleeping). There were documents attached to it to give me more details of those. Of course, I'm not that dumb to open those attachment with my PC. I knew something was up...and suspected maybe the previous virus had my webmail account address and/or password. But, the weird thing is, over the period of two weeks which I had the virus, nothing of this sort had happened. I didn't think much about it and chuck it at the back of my head as I really wanted to work on my paper.

I ran a security check on my computer, but there appears not to be a virus detected. However, a little while later, BitDefender informed me that they suspect trojan is lurking around in my computer.

When can this nightmare end??? What is Trojan anyway?? I'm this innocent gal who's a responsible user in the virtual world, with currently four security systems in my computer.

How can this happen?? Heeeelllllpppp!!!