CindyH:
Check to see if you can see a LIGHT through the vent on the right side of the printer while it's warming up. If you don't see a light, then the bulbs are likely blown (both blow at the same time, and it really is a service item that people should expect to replace on these printers).
HOWEVER! I suspect that you've got a dirty drum temperature sensor. Open the top cover, lift up the teal Lower Exit Guide, remove the teal Rapid Release Guide (has two tabs that you lift off to remove), lift up the white plastic (with writing on it) drum guard. On the left, you'll see a white plastic sensor that rides over the drum. It's a pain to clean it without removing a few other things, but you can run a SOFT *SOFT* cloth between it and the drum and it will provide you with at least a temporary fix. Also, the sensor's electrical connection could be loose (although, you'll usually just start up and get the error when that happens).
TO REPLACE THE BULBS: I've got a complete set of instructions with photos. Send me an email - sppeednet at yahoo . com - and I'll email them to you.
Whit / iFixPrinters