When I started my laptop up the other day, nothing was functioning. I couldn't open any applications and the thing was absolutely crawling like there was no free memory. After a few restarts it started running back at speed. However, when I use it now there will randomly be icons missing from my desktop.

Things such as my computer are simply not visible on the desktop. I can still access programs via the Start menu but obviously this is annoying and perhaps the indication of a bigger problem. Can someone please tell me how to fix this?