Latitude D620 does not get to POST

My Latitude D620 will power on but not even get to the POST (power on self test).  A few days ago, I was using it, all seemed normal, it just froze.  No response to keyboard or mouse except that caps lock key would still turn on/off the caps lock LED.

I powered off and left it overnight.  Powered on, it made it past post and booted Windows XP.  After login to XP, it froze again, same symptoms but this time the display turned all white.  Powered off and on.  It got to the Dell POST, I was able to press F2 to enter setup then again went all white (while in BIOS, not Windows).

Now it will turn on but, the hard drive and fan will start to spin up as usual, leds light,  but stops.  Then only the power led is lit.  No spiing drive, no fan.

I have tried removing and resetting the hard drive, memory (both sticks).  If I leave out the memory and boot up, the LEDs will flash 45 times then it powers itself off.  So it seems it still has some self diagnostic ability.

I have also tried using 1 memory stick and swapping them.  I don't think this is bad memory and not a hard drive as it would still get to the BIOS with a bad drive.

Would a bad CMOS battery cause this?

Thanks.