It may be a java problem. Use the Add/Remove programs Control panel to remove all Java versions, then install only the OFFLINE version which is about 15 MB in size Download Java software from Sun Microsystems as installing over the internet frequently results in corrupt installations.

Deleting the LW preferences folder 'might' improve things.

Make sure you defragment your hard disk drives periodically. Programs like LimeWire with constant downloading fragment drives very quickly. Fragmented drives result in slowing the computer down as it takes the computer much longer to find information (parts of the files spread all over the place.)

I personally choose a different drive to save my downloads to. In this way it lessens affects on the system in the way suggested. On my mac I also run my LW from a separate partition though don't think that is possible on windows.

If still nothing improves .. post these details: System details - help us to help you (click on blue link)