I have a similar issue and have contacted support about it.  They suggested a new video card, but I'm not too sure that will fix the problem.  Sometimes the PC starts to load Win xp, some times it doesn't even get that far and just hangs after the power up test.  Anyway, the video card is still "on order" so who knows when I will actually get it.  I received my 9100 in late March, and it hasn't been right from the start.

The one thing that I have noticed is about 3 out of 10 times, the backlight on the LCD screen does not kick in and I can barely see the Windows XP Welcome Screen. If I hit the suspend button, it will usually refresh the video and the backlight will kick in and everything is ok. Anyone else seen this??

My 9100 had the same problem.  It would do one of two things, either not power up, or power up and just sit there.  No screen or anything.  Just a flashing caps lock light.

Turned out to be a bad RAM chip.  If you have two of them installed, try turning on the computer with them in one at a time and see what happens.  Mine would power up with one of the chips installed, and then sit there and do nothing with the other.

Dell replaced both of them and it's been working flawlessly ever since.

HTH.