Installed Mountain Lion - Now my IMAC hangs in a short loop (1 sec) at least once every other day.

Updated my IMAC from Lion to Mountain Lion. Processor 2.93GHz Intel Core 2 Duo, 4 Mag 1067 MHz DDR3. Now (usually when I am running two software items) my IMAC hangs up about once a day or so. It seems like a short 1 sec repeat. At that point the only way to stop it is to shut down using the main power button. Is anyone else having this problem? I never had a problem until I upgraded. I'm 99% sure it must be in the operating system. Can anyone tell me what's going on? Has Apple found this glitch in Mountain Lion and will they be coming out with a fix?