computer not booting, stopping at DELL splash scree

[NickBVC]

We have a Dell 4550, which is a little over a year old (so
no more support). All of a sudden, we are unable to boot
it 75% of the time. If we turn it on, we only see what
appears to be the top triangle of the DELL logo. The rest
of the screen (including the F2 and F12 in the top right)
is missing. Hitting the power button and then hitting it
again works sometimes. Sometimes we have to hit it a few
times. When it does this (going to a black screen with the
top of the E (a blue triangle)), it just sits there.
Restarting the computer always seems to bring up the
problem. I upgraded the BIOS, to no avail. Not sure what
could have caused this. Latest version of Zone Alarm or
update to Norton Antivirus may have been the last things
installed. No other noticeable problems once it passes
this. Any ideas?

 

[JimWae±]

problems that early are usually either BIOS or hardware, not any
applications