Deffinately sounds like the PSU, i would guess that processor alone requires at least 90-100 watts for operation, perhaps core temperature being raised quite high for more demanding applications could be down to the heatsink not getting enough power to cool the processor sufficently. For the...
If you have a wireless/cabled router that the ps3 is connected to, i suggest using TVersity to setup a media server that your PS3 can connect to to view media files from your pc. To save electricity, whenever you want to watch a film or programme on your PS3 just copy them and turn off your comp.
Perhaps the hard drive developed bad sectors right where vital system files were,due to a lack of file fragmentation the re-install probably placed those files on undamaged sectors by luck. I'd run a HD error check just to be sure no other files will be affected by possible bad sectors.
Try and find an auto-detect option in BIOS and see if the hard drive comes up.
If it doesn't show up i would guess a faulty connection, faulty SATA controller or faulty hard drive. try the hard drive in another laptop if possible, if it shows up on the other then assume its the sata controller...
does your BIOS keep changing to random settings or default settings?
if it keeps going to default then maybe your battery or CLR CMOS Jumper has gone dodgey.
have you tried uninstalling the driver for the monitor and restarting the system?
no "thermal paste" isn't hazardous :chk:, it's certainly not recommended, as it doesnt allow the heatsink plate to fully come into contact with the processor roof. In most cases you'll find the processor to just run at a slightly higher operating temperature, slightly reducing your processors...
Printers can be so tricky sometimes lol, first of all you won't find drivers installed in add/remove programs to find out if your device has a driver installed: it will be under Device manager>"your printer here"> properties. Have you managed to locate the driver directly from dell? (always try...