Problems like this in iTunes that I used to have in Mac OSX could only mean a corrupted iTunes library file. The only way I remember to fix it, is to delete the iTunes Library file. I remember how annoying that was. It was every two/three months my library file would become corrupted and I had to delete it. If you suspect that a messed up MP3 caused the issue (which is what happened to me) then you must get rid of the MP3 that's causing the problem. Try to get a fresh copy of the song, by either ripping it from a music CD or by purchasing it from Amazon.
I was just about to post asking about how to get rid of iTunes in Windows 7. The program has just about gotten to my last nerve, plus now the iTunes store doesn't work (hasn't for at least a month). I have found that for playing MP3s I've had more success with Real Audio and WinAMP, than WMP and iTunes which are the leading MP3 programs. I suppose the only reason why most Windows users use iTunes is due to it's compatibility with iPods. I'm not getting an iPod for myself (have gotten 3 for my daughter who lost all of them).
I saw iTunes in my husband's old Vista laptop and I wasn't impressed, too many crashes of the program, equally in Windows 7 the program is just as annoying. Unfortunately.