Had a problem which began yesterday. Got a blackscreen at boot. I managed to "fix" it by pulling out and plugging in the video card a few times.
Today I again got black screen at boot. Re-plugged in the video card and was ok but then the screen went black at the windows screen.
I think my power supply may be weak (it's around 5-6 years old).
I have a DELL dimension 8300, with 305W Proprietary dell power supply. Video card is Radeon x800XL AGP.