Vista - Vista stops booting after all updates are applied an 3 power offs

Hi all,

I bought a Dell Inspiron 6400 With XP PRO SP2 (Jan 2007).
I bought another 100GB 7200RPM 3.5" HDD for Vista Ultimate Full
(about 2 months after)
The XP SP2 Drive has had the same install, since purchase.

Vista Ultimate Full is another story:
I have had it up & running well. For some reason during the end of the
second week or so, after all the updates Windows updates has that I need, are
installed, I'll Power Off the notebook. When I go to power it on the next
day, it will try to go into Windows, then it reboots. I try safe-mode next,
no luck.
Last known good(config) next, same thing just a reboot.
I then broke out the DVD & tried the Repair option
(which is down below install on the lower-left corner)
It starts this process, but will not stop, or freeze, but it never finishes.

What should I try next?
I'd like to get everything on this, & image the OS with all my apps.
installed, I have just never gotten that far. I'd really rather not lose the
data, that isn't backed up, even though it is only 1 1/2 or 2 days of work.

Has anyone ran across this before, with Vista Ultimate?

My specs are:
Vista Ultimate
T7400 @ 2.16Ghz
2 x 1GB of DDR2 533Mhz
100GB Hitachi 7200RPM TravelStar
256 X1400 with Hypermemory sharing up to 700MB of system RAM
(In Battlefield 2142 it uses 956MB for textures etc..)
2GB Cruzer using the whole 1.84GB that shows up, for ready-boost.

I do use a Anti-Static Wrist strap to remove & install the HDD's
after powering down, pulling the AC plug, and removing the battery. Then
holding in the power button to remve any residual power.

I did install XP home on this same drive after the second failure of Vista
and that was stable for almost 4 months before I decided to put Vista back
on.

This system passes all Diagnostics.
(with either HDD installed)
Dell [whom I bought Vista From] gave me the advice to do a clean install
twice.

Any help as to why this Vista Ult. 64 bit just stops booting into the OS, is
much appreciated. Strange is that everytime, It isn't when I've switched a
drive, but after it's been in the 6400 for several days, and just powers off
normal, then..poof...It won't power back on.

I use

AVG 7.5 Internet Security
PSP XI Photo
Nero 7.10 Ultra Enhanced
AnyDVD, Clone DVD2, CloneDVD mobilie
DVD Shrink 3.2
Several games:
COD2, Flight Sim X, Rallysport
Dungeon Seige, God of War,
TestDrive Unlimited

Thanks Again,

JC


P.S. Sorry about the length I just wanted to be thorough
--
One step closer to the edge...