Hardware :: Fedora 11 Server Will Not Boot On Upgraded Memory?

I run my linux server on the Fedora 11 x86_64 flavour of linux. It did have 1GB of DDR SDRAM PC2700 (Crucial) in the first DIMM slot. It worked fine, however i felt the need to add more RAM to the server. So I purchased 2Gb from Crucial 2 * 1Gb memory stick of DDR SDRAM PC2700 333 CL2.5. However when these are used the machine goes through grub begins booting and then hangs. Sometimes it goes through to the login screen where it hangs, othertimes it hangs after logging in. I have performed a memory test and the results come back fine. However if I just use a single stick of memory the server boots fine (Either stick of memory works).The Machhine is dual boot and my XP professional partition always boots fine