First off, if you're unsure about what you're doing and the computer is still under warranty... don't do anything that involves opening the case. In most cases, opening the case for those crappy distributors (dell, gateway, compaq/hp, etc.) voids the warranty and a sticker is placed over the opening panel so they will know if you've opened it.
But yea, if you feel comfortable rooting around inside, it does sound like a memory problem.
<a href=\"http://www.democracynow.org\"><img src=\"http://i5.photobucket.com/albums/y165/smileygladhands/linkbanner468x60.gif\" border=\"0\"></a>
\"All over the place, from the popular culture to the propaganda system, there is constant pressure to make people feel that they are helpless, that the only role they can have is to ratify decisions and to consume.\" -Noam Chomsky