Hello Jthack,
Need a little more info before we can start helping you.
#1 System specs:
OS
CPU
MOBO
etc
etc..
#2 If you will attach some minidumps to your post they can be used to help debug/diagnose what is causing the problem. The default directory for these is C:\WINDOWS\Minidump ..You should be able to fit 4 or 5 minidumps if you zip them in a folder and then attach them.
#3 any additional information you think might be helpful..What happened when this started happening. Did you install any new hardware and/or update/install any drivers.
I can not say anything for sure as of yet, but if it shuts down and you can't turn it on for a few hours it may be a heat related issue. It needs time to cool down before you can turn it on again. Just a thought, however like I said I can't say for sure what is causing it as of yet.
http://www.majorgeeks.com/download337.html That is a download link for speedfan you can monitor your cpu/case temps and see what rpm's your fans are running at.
I await your reply.