Hey, I have a G4 myself and I recently started having troubles similar to yours. Every time I downloaded an item my computer would freeze up. These suggestions might help if your still having trouble. Try assigning more memory to your application ar if you haven't upgraded the amount of memory in your machine, you might want to, memory is real cheap right now and it wouldnt hurt to have your programs run better in general. It could also be your internet connection possibly if your using 64k you might wanna upgrade to dsl or cable. If your still having trouble just save all your LW files and reinstall. Please let me know how things are doing for you my fellow G4 owner.
Peace
TREE