This is a problem with HD space and Virtual Memory.

So, here are some suggestions for reducing memory used when running LW.

be selective in sharing files. Share the rarer files, but fewer .

Download fewer files at a time, and try to keep the incomplete folder as clean as possible.

Try to keep at least 2GB free space on the HD. OS X needs lots of free space for Virtual Memory.

Turn off LW whenever possible. Running for more than 24 hrs can really eat up the Virtual Memory. Your OS X's "Activity Monitor" (in the Utilities folder) can help you see how much LW is using of the machine's resources.

Of course, a newer faster machine with loads more ram and free space is always the easier solution