Issue with startup

I have had an old Dell Optiplex GX620 sitting around for about a year not running. It had a few modifications made back in the day, new extra RAM and HDD's but worked like a charm until I got a laptop and stopped using it. I tried to turn it on a few weeks back and it didnt work, went to some bluescreen, so I opened it up and blew all the dust out just today hoping this might rectify the issue as it was pretty darn dusty in there.

It runs windows xp 32bit, 2 gig of ram, pentium 4 3Ghz, 280W power supply.

When I startup it goes to the black screen prompting to start in safe mode or in last known successful startup profiles. Whichever option I try it has a long list of files that then run down the page (checking fo rdrivers I think) until it finally reaches a blue screen which displays the following;

STOP: c0000218 (registry file failure)
registry cannot load the hive (file):
\systemRoot\system32\config\SOFTWARE
or its log or alternate.
It is corrupt, abscent, or not writeable.

Beginning dump of physical memory
Physical memory dump complete.
Contact system admin for assistance.

Is it dead, or can I fix this?