Q: Macbook (white) running 10.6.8 - cursor freezes

I have a white macbook (2010 model), running OS 10.6.8 - and just recently the cursor has started to freeze when my computer comes out of sleep. Everything else works fine, and I can click, but the cursor does not move. When I plug in a USB mouse, the cursor is fine, and if I then restart the computer, the trackpad respnds normally again, but once I shut the lid, and reopen, the cursor has frozen again...

Any ideas for what I can try here? I can't find my original installation disk either...