Usually the awkward SOB sullenly sits there in defiance until you reset the machine or pull the plug. At least you can read the unhelpful error messages at your leisure.
However, if your Windows 7 or 8 should go BSOD, you want to read the exact error message without the re-start; you might at least be able to search the web for a cause and solution.
To prevent the automatic restart in Windows 7 and 8, press the Windows key, type Advanced, select View advanced system settings option, click Settings under Startup and Recovery, and uncheck the Automatically restart checkbox.
This may give you a fighting chance of tracking down the error in the unlikely event of a Blue Screen. AJS