I have been experiencing the same crashes as you all. I have a G4 with 512 mg, and huge amolunts of HD space. I actually stopped using Limewire when I needed to replace all the data on the hard drive and more.

However, I think that the problem may be due to incompatibilities in the MRJ files from Apple. I have now disabled the FAXStf files, and hope this solves my problems. I think it will stop the crashes when I click on the menu bars (Apple refers to this specifically.)

Check out the Apple support site and get more info on this for yourself.
B.