Screen shutting off, not coming back on. HP nc8430 XP

I think that's a long enough title

If I am away from my laptop a while I close the lid as I am paranoid the screen would get damaged with crazy people running around, but I leave the laptop switched on

The thing is, sometimes when I open the lid nothing comes onto the screen. Just a blank screen (that is on as I can see the back light). The laptop is still on. If I press the power button, half the time the problem fixes itself and the other half I have to force a shut-down and restart by holding the power button (is that good for the machine?)

Power settings (its always on AC these days):
Turn off monitor: Never
Turn off HD: Never
System standby: Never
When I close the lid: Do Nothing
When I press the power button: Ask me what to do
When I press the sleep button: Ask me what to do

Now this never used to happen... its literally like a recent within the last 2 months thing (I was hoping it'd go away ).

Thanks. Its gone 1am so I'll read (hopefully!) responses in the morning

 

Come on... come on!

Another thing to add. Sometimes I would half close the lid - so enough of the hinge comes down to press the 'switch off screen button' but leaving a gap so sound could come out clearly. I do this for music

Never had a problem doing this until now. Now when I do that the laptop seems to go into standby See power options above. My wi-fi gets disconnected as well. Even if it is wi-fi related, there is no point testing with ethernet connected as I must use wi-fi

Thanks?

 

It's been a while since you posted about this. I have the exact same problem and didn't know if you ever came up with a solution. I 've always suspected the HP Credential Manager, as I'm using fingerprint login, but nobody else at my office is. But only one other person at my office has the problem and he has the model without the fingerprint scanner.

If you ever found anything out then I would appreciate hearing the solution.