Cant shut down MacBook

I tryed all the basic troubleshooting things except the ones that required rebooting because I cant shut down. I think I downloaded something stupid. The program that is preventing me from shutting down is limewire. I think the movie I tried to download is the bad guy. I tried deleting the movie but it says its being used. I tried force quit, nothing. I deleted everything that I downloaded or tried to last night. There were several caches that wouldnt delete because they were being used. I dont know what else to do...somebody please help.

Press and hold the power button.