Locking up - process terminate process

Hi, 

I am finding that again and again, SL360 "locks" up when left open on my Desktop, if, for example, I go away and get a coffee, or do another task like email. I only have to leave it open and unattended for 5 minutes, and have to CTRL-ALT-DEL and terminate the process.

Is this something that anyone else has experienced before, or is this likely to be a setup thing on my PC?

Thanks