i hope you didn't double-click any of those setup.exe files...
Files that are smaller than usual music files are quite often viruses.
Just because it's a small file does not mean anything in particular.
A lot of applications that are written in Assembly language are very small and sometimes virus files are written in that same code.
Be careful never open one of those files whatever you do.
As for LimeWire perhaps you could try downloading and re-installing LimeWire and see if that makes any difference.
Otherwise Read all the "Sticky" threads at the top of these forums and hope that a solution to your particular problem has been mentioned.