Scraping sound coming from Theta Transport


Why do some cd's make a strange sound like somethings scraping inside my Theta DaViD? I actually own two of these units and certain cd's make srange loud scraping sounds during playback. I've check the discs in other players and they play fine, but neither of my Theta DaViDs will play them. Enya, Norah Jones, Sting (DTS disc) Forget it!

If anyone has a clue please chime in. Theta was no help on the phone. They just play dumb, like no one has ever reported this problem before. Maybe I have the only two units that were ever affected?
128x128glen
Ha! My Carmen skipped like crazy on a bunch of disks, and just plain coughed up a few (of course, no other player responded this way). The factory had it 3 times before they would replace it under warranty - took nearly a year. They played dumb with me too, said it was my disks, etc. etc...

Great sound, but bad, bad service. BTW, enya discs seem to be particularly prone. I'd LOVE to hear the real explanation for this phenomenon.
Thanks for the info. I am in the market for a transport. I am not getting a Theta.
my DaViD II seems to have problems reading HDCD's at the beginning of track 1...doesn't happen with redbooks...makes that kind of noise as it tries to track...doesn't happen with DVD's...I'm wondering if it's the laser...I'm trying to "track" down the problem myself