Battlefield 1942 multiplayer demo Help needed (pc restarts)

hi, ive dloaded the battlefield 1942 multiplayer demo and when i run it about 1 or 2 minutes into the gameplay the pc just shuts down and restarts (rather quickly),

this only hapens when i try to play this game, i can play other games for long periods of times with no problems, only this game is causein me issues, i wanted to play the demo because i waned to get into the whole batlefield series games, and to be honest my pc is not strong enough for batelfield 2 (until i build a new system later on this year) i wanted to try the demo before i would buy the ful version of the batlefield 1942, im using win xp home edition, sp 1, i have intel pentium IV 1.7 Ghz, 521 mb's of ram, and a ati radeon 7500 all in wonder (64 mbs), and a 480W psu, the newest dx9.c update, and the ati cataclyst 6.4 or so or 3 maby (i cant get the newest ones they do not suport the 7500 series gpus) so my system is way above the recomended requirements(not mentioning the minimum ones),

soes anyone know what migh tbe the issue?

thx for all replies

.... will buing the game fix my problem? i wanted to try out the demo first, if i have issues with it i might have problems with teh ful game, so i didnt want to waist money on it.

ill check it out, thx

thx for the info, i actualy went to eb games yesterday and they had a batelfield 1942 complete colection ...i think that was the name of it, so it was the game and 4 maore pacs for 19.99, i was actualy thinking of geting it, would it be worth it? are the gaming packs interesting? and worth the aditional $$ are they playable online?

thx