Some time ago I was asked to fix the following issue on a MS Vista Home Premium SP1 desktop:
a user would be constantly getting a black or blank screen after booting into the PC.
After doing some initial research first using the most popular search engines I was not able to arrive to the proper solution.
How I did resolved it:
I noticed that I can click Ctrl-Shift-Esc after the OS booted to get to the Windows Task Manager.
What stroke me was that Explorer.exe process was not listed in it! As a side note, Explorer.exe is the process responsible for loading the Desktop [view].
This is exactly I thought what I need.
I started it by using File|New Task (Run...) and typing in Explorer.exe.
At this stage the Desktop magically appeared, hooray, no more black screen!
Now I needed to figure out why it would not come up again after a restart.
So I went to the Start menu and found the Windows Explorer in there (in Accessories), did a right-click on it,
and in the security tab I saw "Run as Administrator" enabled, that was not a typical setting, however that looked legit to me.
Nevertheless, I decided to disable that option and restart Windows.
At this point and onwards new sessions started normally, without the black/blank screen coming anymore.
PS: I do not know why this setting exists if by enabling that it leads to such serious consequences.