256 MB ram is not a lot nowadays.

How are you & your sisters set up. Do you all use it at the same time? Are you all networked together or have separate connections to the cable?

1st try deleting your LW preferences folder; instructions here: Fixes for Limewire

What other programs do you use at the same time?

If this is the 1st time it's happened & you've used it successfully before, then try reducing your shared files. And your incomplete files. Go to your incomplete folder & list it in size mode. So then the largest are at the top & smallest at the bottom. Now delete those that are 0%. After opening LW, go to your download window & click on top of Progress column which will organise the files by %. Then delete all those at 0%.