I've resently installed both PC versions of FF7 + FF8 and BOTH are having the same problem strangly

FF7 - full install, using 1.02 patch + swirl fix + FMV copied to hdd + hi-rez fix exe + standard rez (backup of exe)
FF8 - full install, using 1.2 patch + FF8 launcher 1.31 (fixes black boxes issue)
BOTH games work fine, until around over an hour play, they just seem to stop working.
The gfx hangs, but the music and sfx can still be heard, strangly it happens on both game, more or less similar time frames.
They are the only games this happens in

i can play the games fine, just need to quit out every hour an reload the game up which is anoying.
System -
E6600 Duel Core
2GB RAM
512MB GeForce 7950GT (175.70 drivers)
WinXP SP2
any ideas would be fab... tho at a guess, i would need to revert to a very old driver set.. like 97.49 or something, which i dont really fancy doing just to play these two games.