I have an almost 3-year old XPS 400.  Starting yesterday morning, I have had trouble getting it to boot.  I press the power button, the fan starts, the HDD light comes on, the diagnostic lights flash a little, and then after about 5 seconds, it goes no further.  The power button is lit (green) and I hear the fan, but I neither see nor hear any HDD activity, and the monitor remains blank or briefly fill the screen with a bunch of jumbled characters then goes blank (the monitor power button is on but amber).  When this happened the first time yesterday morning, I just hit the power button to turn it off, then after a few seconds, turned it on again without any problems.  Yesterday evening it took me around 7-8 tries of turning it on and off to finally get it to fully boot.  Just now, it was about 12 tries.  I should also mention that usually on these failed attempts, all the diagnostic lights turn off, but I occasionally have 1-2-3 remain lit.

The problem appears to occur only on the first few seconds of booting; once WinXP starts loading, everything appears to come up as normal without further issues.

I'd appreciate anybody's ideas of what may be wrong!

XPS 400

Pentium D  3 Ghz

WinXP Media Center Edition SP2