Try my 'Freezing' guide, though I don't think overheating is likely!
Many possible causes of freezing.
1. Check out your OS
First try System File Checker
Winkey plus 'X'
Choose Command Prompt (Admin)
Type
sfc /scannow then
Enter
It finds and fixes errors in Windows, but doesn't always report them. Run it and see if the fault disappears after re-booting your system
If corrupt files are found that can’t be fixed, try
Dism /Online /Cleanup-Image /RestoreHealth
Re-run SFC
To view CBS Log
findstr /c:"[SR]" %windir%\logs\cbs\cbs.log >sfcdetails.txt
Search C drive for sfcdetails.txt or navigate to C:\Windows\System32 and scroll down.
2. Check System for overheating
D'load and run Speccy
http://download.cnet.com/Speccy/3000-2094_4-75181811.html
Check temperature after running a game for a while.
(Click Green tab next to Temperature for real time graph)
3. Check RAM.
If you have more than one stick, try running on one at a time. Or run Memtest 86.
Best run the bootable version, as it checks out the areas of RAM normally occupied by Windows.
http://www.memtest.org/#downiso
Then create bootable CD or USB Flash
4. Check HDD for mechanical errors
http://www.seagate.com/support/external-hard-drives/desktop-hard-drives/freeagent-pro-classic/seatools-win-master/
or
http://support.wdc.com/product/download.asp?groupid=606&sid=3
Bootable diagnostics
http://www.seagate.com/support/internal-hard-drives/consumer-electronics/ld25-series/seatools-dos-master/
Update Drivers, especially GPU
If Desktop, exchange GPU if possible.
6. Generally check for poor connectivity.