Blank screen at start-up

I've a Packard Bell desktop PC running Vista Home Premium (32 bit). Have had it for a couple of years. Have kept up to date with all relevant updates.
On Sunday when I turned on my PC and screen the screen did not display (remained black). Windows loaded and I then turned the screen off and turned it back on again and lo-and-behold the display was OK and remained OK thereafter. The same happened on Monday so I did a system restore to last Friday (when all was working OK). Today (tuesday) the same - black screen on start-up - occured. So I turned the screen off and on and again all was OK.
I had not added any software between Friday and Sunday, I do not use any 'hibernation' type functionality.
If I do a restart the screen displays OK.
Help I'm a bit lost as to what may be causing this behaviour ?
Any advice greatly received
Thanks
Bazza

HI,

If when this happens the screen stays black and never displays anything. P.O.S.T. or PB logo then it isn't software.

It sounds as if it is most likely the Monitor, much less likely the video card.
The best test is to try the monitor on a different computer and see if the trouble happens.

The Dell monitor I'm using does something similar. I have to have the computer running before I turn it on or I have to power cycle it to get a display. When I switch the KVM I have to make sure to select a input that has video or I have to power cycle it. Sometimes when I switch inputs the screen is funny so I have to switch a couple of times.

Why Am I still using it I hear you say? Because I'm frugal and it is paid for. When it drops completely dead I'll replace it.

Try the trouble shooting test I gave and Good Luck
Roger