|I note what you are saying about the overheating and agree that from what you describe it sounds unlikely. Just the same, if you are inside the computer there would be nothing lost in cleaning up the vents and CPU heatsink against this slight offchance.|
I note that you have minimised startup programs but the reason I suggested unchecking in msconfig startup was to see if there is a problem with one of these which is causing the issue.
When the clock shows silly times it is almost always due to the BIOS/CMOS battery failing, although this doesn't fit very neatly with the other symptoms you are describing.
Maybe there is more than one problem.
The BIOS/CMOS battery apears to be one of those coin shaped types that you just pop-in. I would change that for starters as they are very cheap and easy to fit. The motherboard manual (showing the battery as BT1) can be downloaded here:
The battery is probably a CR2032 lithium, which is widely available.
If that doesn't help then try to see if knocking out anything from msconfig helps at all.
What we need is to get some sort of handle on this issue but it is clearly not going to be too easy.
Always pop back and let us know the outcome - thanks