In searching for info about the on/off problem with the 610XL screen, I ran across your post. Any luck?
When I called Gateway, I was told it was probably a software issue and "surprise", call tech support and pay for an answer.
You're not the only one...
I was given a Gateway 610 series with Windows Media Center. It was purchased new in 2k3. I turn it on and I can see it is a cluster $#@%! It boots up but the monitor is on for 2 seconds, off for 5. It took a while but I managed to run Adaware and deleted 72 files and ran AVG antivirus and it's clean. The entire PC (monitor, hardrive, sound system, all run from 1 power cord.) I assume it's part of the problem. Gateway wants $$$ to tell me it needs to be repaired.
If anyone knows of any tip, tricks, fixes please let me know. Thanks, John G