Need help w/PX-504A

Hi,
About a year ago I installed this burner. This burner was working, but last month I tried to burn a cd, had Roxio burning software. I’m running XP Professional. After doing research found that Roxio didn’t like XP w/SP2 and Media Player 7.0 or higher. Well I have SP2 and Media Player 9.0. So, I purchased Nero Express 6.0. Still the burner will not burn. Looked at Device Manager no yellow exclaimation marks. Went to Plextor site and began searching for answers. They recommended I download latest firmware. Didn’t need to already have firmware version 1.01 currently installed. Short of opening the CPU pulling the device and plugging it back in I’m out of ideas. The drive will read just won’t burn.
Does anyone have any suggestions?
Thanks