Vista - Odd Sleep/Hibernation

I have an HP Pavilion HDX0910NR notebook running Vista Ultimate 64-bit.
About 2 weeks it has begun doing something similar to hibernating. I can be
using the computer without any issues and I will walk away from the computer
for a few hours and come back and there is no HD activity, the screen is
black and no matter what I press on the keyboard or mouse the PC very rarely
responds. On the rare occasion it does only the screen will come back on and
I can choose to open windows but they never open. After a few clicks I still
get mouse movement but nothing responds. I had done a recovery in January
because of some other issues but this just started 2 weeks ago. I have
verified all of my power settings and nothing is set to turn off or spin down
or go to sleep. HP even had me remove the performance setting entry in the
device manager and reboot but that didn' work. I'd like to avoid a reload if
possible. If it helps with a diagnosis, I leave Live Messenger running on
that notebook at all times and i can see it signed in at work and after a few
hours it signs out at home.

I've got some sort of such issue.

HP pavillion dv5 1120er with Windows7 x64 (and Vista 32 on another partition).

When there is free space on Win7 partition became smaller than about 3 Gb, system began to spontaneously hibernate.

Now i'm trying to enlagre that Win7 partition....

Hope it helps.