Ubuntu :: System Crash Every 15-20 Minutes

if my PC lags a bit it crashes!But I wouldn't think it would be an ordinary crash.Earlier today I installed Xubuntu 10.04onto my PC. Well, The installation was smooth and I was able to get it installed. Then all of a sudden when I was looking aroundmy PC got caught in a little lag.. And when it lagged this black screen came up and it said

"Starting Common Unix System; cupsd [ OK ] "
"Checking Battery State [ OK ] "

Then That screen disappears and these Straight gray bars come up and they cover the top of my screenAnd they just blink! I figured it might be a glitch so I went to go eat dinner.About 20-30 minutes later I come back and there still blinking.I tryed rebooting the system and trying again and it got cought in a little lag and the

"Starting Common Unix System; cupsd [ OK ] "
"Checking Battery State [ OK ] "

Came back up and it disappeared again and the bars came back!I tried reinstalling Xubuntu 10.04 but it came out the same result.I tried updating the system cause when I installed it it said I had 164 updates waiting.

_PC INFO_
Dell Dimension 2300 with Xubuntu 10.04 as the operating system
256mbs of RAM

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