Computer display not always showing when turned on
 

Okay, so, here goes.

I have come back for a visit at my 'rents place ofr a month and used a computer that has really not been used for two years. It was bought maybe two and a half years ago (so six months roughly of use).

Specs are:
HP Pavilon
3.2 Gig Processor
180 Gig Drive
512 Megs of Ram
Windows XP


If you need any more, let me know.

Anyway, whenever I turn it on, I MIGHT get the display. My monitor will either show the usual boot up screen OR it will show a screen that it shows when the computer is off. Sometimes I then have to unplug the computer and plug it back in, in which it willt urn back on immediately. One time, when it came back on, it showed hex numbers all over, for a weird, matrix like effect. Cool, and not cool at the same time.

\Now, this does NOT happen if I restart the computer...only when I cold boot it (so far anyway).

I have never heard of anything like this before. Any ideas on what is going on and how to fix? Thanks.