Do you know what Unknown Trojan is?
Unknown Trojan is a new popup error message displayed by a Trojan. It is a simple popup message that may prompt users to click OK to download the rouge anti-spyware program that it advertises. Do not under any circumstances click OK to download this program.
Do you get this error message?
Your computer was infected by unknown Trojan. It's dangerous for your system (critical files can be lost)!
Click OK to download the antispyware program to clean your system! (Recommended)
In non-techie terms: Popup messages that state you have some type of Unknown Trojan or spyware infection are usually false. When a parasite is actually detected on your computer, in most cases, it will prompt you through an actual detection program and not from a generic "System Error notification".