Okay.
Hang in there.
The next time the desktop disappears. Don't restart the computer. Just test the following:
hit [ctrl]-[alt]-[del] of you get a window go to the TASK MANAGER button. once in task manager
go to file --> new task.
you will get a box.
type the word "explorer" without the quotes.
that will bring your desktop back up.
report back on that. if you CANT get a window, report on that too.
*****
next up you need to disable any startup processes that may be causing the problem.
The next time you shut down the machine, you need to bring it up in safe mode. tap F5 once a second while booting the machine.
if the computer crashes in safe mode... you have OS repair job on your hands.
If it seems to operate okay in safe mode, you can go to msconfig and eliminate all the non Microsoft processes from startup.
That's START -- RUN type msconfig in the bar and hit enter.
That will bring you a window.
In the tabs you have General, system.ini win.ini boot.ini services, and startup.
leave all of the ini tabs alone.
In the services tab: on the bottom of the window make SURE the box beside "hide all microsoft processes: is CHECKED.
double check that.
it IS checked? okay. click the disbale all button, and the TRIPLE CHECK that hide microsoft thing, and then click apply.
in the STARTUP tab click the disable all button, BUT DO NOT APPLY YET.
go to the list.
click the check box next to the following items:
avgcc if you have it.
ctfmon
isuspm
atiptaxx if you have it
synTPLpr if you have it
click apply.
go ahead and restart normally.
at this point, if the computer behaves properly, and doesn't crash, you know you were dealing with a rogue process somewhere in the disabled list in msconfig.
you can add them back one at a time untill you get the problem.