If you are having RAM related issues the first thing to try is removing each module, be sure there isn't a dust bunny in the slot, and then reinsert the module, being sure the clips close around both ends of the module, indicating it is fully inserted and locked in.  If problems persist and this is happening with brand new modules, you may have incompatible memory.

I have a one year old inspiron 9400/1705. The other day I was just looking at some of the system stuff, noticed it said 512mb ram, supposed to be 1gig, Unhooked power and battery, removed ram cover, unplugged re plugged both 512's and hooked up again, now shows 1gig. Do not know why, laptop has never moved from the desk, never, no travel nothing. Just loose or not inserted correctly and the factory, but now all is well.