edge:

semigeek: Has anyone had any problems where their computer goes into Sleep mode, and then approximately 30 seconds later, it wakes back up again without actually touching anything like a keyboard or mouse? 

Sort of.  My main issue was that the computer refused to sleep at all automatically.  If I manually put it to sleep (usually at night) It was always lit up like a Xmas tree in the morning.  What I don't know is how soon after going to sleep it actually woke up again.  Searching the interweb thingie I found one option was to disable wake timers:

Settings > system > power and sleep > additional power settings > change when the computer sleeps > change advanced power settings > expand the "sleep" tree > expand "allow wake timers" and set to "disable"

This stopped it waking up again (but didn't fix the not sleeping issue) - however, I am not enough of a geek to know exactly what disabling wake timers was doing - i.e. whether there was some other disadvantage in disabling these timers.  Someone with more knowledge than me would have to comment, or maybe you know that yourself.

BUT - getting back to the original issue of not going to sleep, the solution appeared to be to uninstall all the usb drivers in device manager individually and restart the computer to reinstall.  This has totally fixed my "not going to sleep" issue.  I have now just gone back and re-enabled wake timers just in case the usb re-installation has fixed that as well.  I haven't done it overnight yet so cannot report on whether it will start waking up again after any length of time.  Will report back if I find anything useful.