Catherine, when you say hang I assume you mean that the application doesn't respond and your getting the spinning beach ball? What version of Mac OS are you running? How much free space do you have on your hard disk? I'm going to suggest that you run Disk Utility but how you need to do that depends on which OS you have.
Thanks for responding
Mac OS is 10.7.4
Hard drive - 1T with 799 Gb available
The beachball, yes, is appearing, but if I click somewhere else - like another window or program, it stops on the program where it was hung up. If Im viewing a tutorial movie or an imovie, the sound continues, but the video stops.
I've had programs totally freeze, but this is different as it lasts only 15 -30 (only an estimate!) seconds and can be stopped by clicking elsewhere and happening in several programs.
Let's hold off on Disk Utility for a bit and go back to Activity Monitor. Here's a link on using it
In the drop down menu select All Processes, look at the CPU% column and see if something there is hogging all of your processor.
Most of the items are around 4%. When I'm running a movie, shockwave is about 12%.
In the mean time I have deleted an app that kept popping up to be upgraded - PocketCloud. I could not stop the app through the activity monitor and was able to use the dmg file and uninstall it. I'm thinking that might have been the issue, since the "freezing" hasn't happened since deleting (but I may be speaking prematurly!)
I did run disk Utility and all was well with verify and verify permissions.
I appreciate your help.
BTW - looking at the system temperatures the graphics processesors are over 150° Do you know if that's normal?
I don't know if that temp is normal. I don't monitor any temps unless I'm having a problem, and I haven't had any issues like that with my iMac. One fifty doesn't sound out of the ordinary to me...but I'll leave that to someone who does monitor their temps. I hope you found your problem, if not post back and we'll get back to it.