I have seen some similar problems here on the boards, but didn't see anything quite the same or a solution.
A formerly trouble-free clone running XP Media started up this morning with its monitor giving a no signal message. The monitor has been tested on a laptop, and is functioning normally.
Rebooting the machine various times has failed to avoid the problem, but it has kicked in at different times. I have once managed to log in, and have the signal cut out as the machine was struggling to find the user desktop settings. Sometimes it starts with no video and no 'no signal' message, sometimes the 'no signal' appears just after the bootup sequence but before the first Windows screen appears. Most often the machine manages to reach the login screen, and then the signal cuts out.
It is impossible to tell if machine is stalling - it continues to run at least after the video failure.
I have no other video card to test.
I have no knowledge of any downloads or installations to the machine in the past 24 hours, and will check this. There have been no hardware modifications or additions to it.
Hope that someone here can help!
Thanks in advance for any suggestions.