Sleep Problem- Screen Dims- Must Force Restart

[neonart]

Recently my Quicksilver started giving issues with sleep. Often- in fact, almost everyday now- it won't go to sleep. When I hit sleep, the screen dims from top to bottom and a warning says I have to hit the reset or hold the power button.
Sometimes it will go to sleep, but then it won't wake at all. I must restart the thing.
I've searched here and on Apple's site and have not found anything. Has anyone experienced this? Do you know of any common causes for this?
Your help is greatly appreciated!

 

[neonart]

From what I can tell, this "warning" is actually a Kernel Panic. But still not sure what's causing it!

 

[timbloom]

first, check that you have the latest firmware for your powermac
second, have you installed any pci cards? some pci cards do not support sleep and will not play nice when you try to put them to sleep.
if none of this is true, try to run all the basic diagnostics, like disk utility, repair the permissions, then reboot and see if that helps.
otherwise you might have something wrong to the point you need to reinstall the OS
if this is the case, backup your stuff, and reinstall the OS from the cd's, see if this fixes the problem.. if it does not.....
i hope you bought applecare or it is still in warranty

 

[Freg3000]

I had MAJOR problems with sleeping and kernel panics. The good people of MacRumors saved me.

It was a bad RAM problem causing my problem, so if you have ANY third party RAM, ANY AT ALL, pull it for a while and see what happens. I even ran the Apple Hardware test-which said that everything checked out.

MacRumors knew better......lol

Good Luck.

 

[neonart]

I think I found it.

It looks like it was bad juju between my Griffin Powermate and my USB PCI card! I had recently removed the powermate from my keyboard and move it to the back of the machine on a PCI card.
I bought a very tine USB hub* from Microcenter and hooked up, my keyboard, mouse and Powermate to one of the motherboard ports and no more issues. I've put the thing to sleep 4 times and it's been flawless. I hope this remains the case.
*BTW, this little hub is AWESOME! Very, very small and light. It's made by IOGEAR and MicroCenter has them on sale for $15.99.
http://microcenter.com/single_product_results.phtml?product_id=0145408

Thanks to all who helped out. I'll post again to let you know if the problem has been vanquished or if it returns.