Toshiba 205-S5825 random crashes

Based on my recommendation, a friend purchased a Toshiba Satellite A205 last May time frame from Best Buy. It was for her daughter, who is probably in her 30s. She uses the computer to surf the internet and as a word processor and to store digital images. So far, however, she has not been able to connect to their Internet server. I have connected through a wireless connection at my home. The laptop has crashed numerous times. We have returned it to Best Buy where they initially restored the software using the restore CD. The computer may work for a while but then will crash and freeze again.

The computer is running Windows Vista Home Premium and I installed 2 GB of Ram. It has an Intel Pentium Dual CPU T2370 @ 1.73 GHz. The last time Best Buy had it, they performed a Ram test, passed, ran all their test utilities and they say it passed everything. All software came pre-installed.

When the computer crashes,the monitor shows colored lines across the entire monitor. I cannot make out any words or icons, best I can describe it, is a quilt of many colors stretched horizontally across the screen. CTRL-ALT-DEL does not work, neither does the mouse or keyboard. The only way to turn off the computer is to remove AC power and the battery. The computer then will not come on right away, it may take 2-3 days. One weekend, I watched a movie, paused in the middle for 30 minutes, then continued with the movie. I left it on for 24 hours the first time and then about 12 hours later. I did not have any issues. It froze on the owner, who played a game and opened a word processor, left for about one and a half hours, when she came back it was frozen. I brought it home, turned it on and it froze within 15 minutes that time.

I know this is long, I have tried to include any and all information about the computer and the issue we are having. Can anyone provide any help? I can take it back to Best Buy, but they don't know how to find the problem. Of course it works fine when they see it!

Please Help!