Why does my laptop freeze and show a strange grey screen?

Hello,

I have an HP laptop that is recently acting up. I didn't have any trouble with it for a long time. It's quite strange.

First, I noticed several weeks back that some windows turn to classic mode instead of aero, particularly with Firefox. No biggie.

But for the past few days, the computer is locking up and the entire screen turns to some grey pixel looking display, it's hard to describe. And if audio was being playing, the audio would hang too.

No buttons function, except holding the power button for 5 seconds for a hard power off.

When rebooting, the first time it's a blank screen after it shows the initial bios screen and then have to power off again like above. Then the second time it gives the option to boot Windows normally.

Today it happened, but it went to the black screen three times and I was concerned that it died or something.

Luckily the fourth time I powered on, and it gave an option I hadn't seen before, it was called Start Repair or something.

So anyway I chose that and for like 1 hour Windows said it's attempting a repair, I came back and it was showing the login screen so whatever it was doing worked.

But does anyone know why this is happening? Is this red flag that some hardware is dying or is it caused by some software?

Windows is up to date.

And just to note it's running Windows Vista.

Appreciate any help, thanks.