I have a Dell OptiPlex 755. After a recent reboot, the system doesn't boot- the Dell screen appears, then the Intel RAID status (has a RAID 1 array), but then simply a black screen. I never see the Windows screen and pressing F8 does not bring up the Windows start menu.
When running Dell diagnostics, the initial tests all pass, but when hitting a key to open the diagnostic partition, it hangs there.
I ran memtest+ from the UBCD for several hours and no errors- system booted just fine from the CD.
However, the Seagate diagnostic program also won't load (also from UBCD).
I've tried swapping RAM chips and resetting CMOS with no progress.