DVD drive won't eject

Try ejecting electronically using something like NirCMD.

If you're running windoze, it is probably some RIAA malware making sure you don't do anything naughty like rip dvds.

Get 'wholockme' and see what process is locking it.

Good idea. There's also Wizmo:

Run: wizmo open wizmo open=E: Requires DirectX

On the Pavilion A250, the real DVD front panel is hidden behind a decorative plastic hinged front panel. If you manually pull down the decorative curved front panel, you should (hopefully) see the eject hole.

However, the symptoms might be something else. I've seen the decorative hinged door jam sufficiently to prevent tray ejections. I've also seen Liteon drives strip out the internal plastic gears, and exhibit the same symptoms. Same with drives that have the tray manually shoved in or out of the drive. You might want to tear it apart, extract the drive, remove the cover, and see if it operates correctly.