Many have aged and a cause of the issue. The 3.2GB ram is very very odd. Not one machine in thousands over the years had that possibility of RAM so I guess that's what a 32 BIT Windows reports.
It is XP so we know that installing the OS is not straighforward.
We also know that the power supply is very important along with heat sink compound, fans and more.
There is some 100 reasons for this machine to lock up given the short story you gave. I see no reason to offer any any reason over the others except to ask you re-check your power supply choice.
Don`t know exactly all my specs, but I have sth like:
windows xp professional sp3
asus p5qc motherboard
intel core2 quad cpu Q8300 2.5 ghz
3.2 gb ram
nvidia gforce 9800 gt
and since I assembled it I started having these problems.
ctrl+alt+del doesn`t work and I have to restart it every time, tried changing the hard disk but seems that wasn`t the problem.
also I noticed that while in some days it doesn`t freeze at all, usually when it happens the problem occurs several times(2-3) in a short period. Also, it freezes if for example I run a fullscreen hd movie or play a game or even after starting the computer from standby.
I thought maybe it`s the graphics card,but could sure use some suggestions.....