There's an "uknown trojan virus" on my computer? PLEASE HELP!? - uknown error looks like spam

Okay, this problem started yesterday afternoon, before my computer was working perfectly. But yesterday I had my computer and keep saying these messages are displayed:

"System Error was! His team hit by an unknown Trojan horse. It's) can lose dangerous for your system (critical files! Click OK to close the anti-spyware program to clean your system Download! Recommended () "

and every time I my computer ok, but when they start going on the AIM and websites, where no news release, and like 10 of them appear in a moment. And I clicked on "OK" to see if she were my system clean, but it does not work at all. I looked online, wherever possible! I can not find anything to solve the problem, if British ColumbiaI download something that's just my computer that is scanned or paid for! And I try to restart my computer, but I have the CD that came with my computer, so I do not know what to do. Can someone help me please? "Pray