Ok, guys I was using this program iMesh for sharing files(music), and I don't know but for some reason my computer started showing all those errors and so on! I don't know what it is...a virus or... I don't know! However now I my whole computer is messed and when i go in it, it starts it right! But when I want to open some file or a folder (even My Computer and My Documents) it just shows me "Explorer has caused an error, Explorer will now close..." So is there any chance you can help me in this one?

Also can you tell me a good anti-virus program, which is like known all around the world or something, because I never used 1 before and I just don't know which one to install! I'd be greatful if you guys can help me with this one as well! Thank you!