ipod 80 gb is saying ok to disconnect but doesnt do anything it stood on that as if its frozen what could i do?

Try a hard reset. To do this, press and hold both the Select/Center and Menu buttons together long enough for the Apple logo to appear. This may take a few tries so don't give up to quick.

B-rock

I am having the same issue. Now the apple logo keeps cycling on and off. Any idea what is going on?

Could be signs of a damaged hard drive or corrupted software. Can you try and connect it to iTunes in Disk Mode? Disk mode will prevent the iPod from continously booting and perhaps allow iTunes or even just your PC/Mac to recognize the drive for you to restore or reformat it.

Here are instructions for getting your iPod into Disk Mode.

Putting iPod into Disk Mode

B-rock