System Freeze

My problem is that after awakening from sleep mode my system occasionally freezes. I may get one screen of the application I select or it may freeze right after I click on the application icon before it opens. Other times it may freeze after running for a while.
I have just recently switched to a cordless keyboard and mouse and wonder if that might be the problem. Has anyone experienced something similar?

I have an iMac 24 2.16 Ghz Intel Core Core 2 Duo, 1 GB SDRAM, 500 GB hard drive and a 500 GB external firewire Western Digital.

Running Snow Leopard 10.6.3

"Freezing" can be caused by either defective hardware, bad and\or conflicting software. You'll need to try to isolate the cause. Since hardware is usually suspected first, what I suggest is boot your iMac with the original install DVD and run the Apple Hardware Test in extended mode. That will check out the system memory, hard drive, graphics, and other components. See this LINK.

Post the results back here and we can go from there.

Regards.

Go back to the wired keyboard and mouse..turn off sleep mode. See what happens.