On my kids PC - XP Home OS - I have three user accounts and two work fine. The third always opens to a desktop that goes black for a second and then re-opens at a low color quality setting. My daughter has to go in and change property settings to High (32 Bit) every time and then it is okay - until she boots up again and it's back to low again.
She was using onboard graphics but I've now switched it to an NVIDIA 6200 card and it still does the same.
Something seems to be instructing it to switch to "Low" but what and where ?