Grey Bar/Firmware password problem

I ran across a system where on powering up in normal mode, the creeping grey bar appeared. It made it a small part of the way across the screen and the system shut down. Doing the Hold the Power Button down till the long tone allowed the grey bar to go all the way across but then the system shut down. The next power up let the bar go all the way across abut then the shutdown happened.

When I tried holding the Option" key at power up to get to the Restore Disk (or even re-image the system) it brought out the Firmware Password entry window. Obviously a firmware password was entered Problem is the user forgot the password. Now this is an Intel system so itmeans a trip to the Apple Man to reset the firmware password. What I am wondering, is there any way to tell what other problem may have caused the Grey Bar (bad NVRam data I suspect) to show up. I do know that similar problems would occur in the older G3 and G4 systems when the cmos battery failed. Is this a possibility in the Intel systems? This would be a 21" iMac probably five years old or so. (Sorry, but I didn't check the SN to track back the exact model when I was asked to take a quick look at it.) I would suspect is does have a "coin" type battery under the cover. Can anyone confirm that and if a bad battery might have caused the original problem?