Just had the same problem myself (Liteon on XP SP2). I went into Device Manager and uninstalled the drive, then rebooted the machine and it seemed to reinstall and write OK after that, though it still wouldn't read and there were a couple other of little oddities. My old DVD reader in the same machine also stopped reading CDs at the same time...
Only happened last night, so I haven't had a chance to see if it is working OK today!