Upgrading my R.A.M. but the system hangs up in Windows 7.

'''Update: There are several false spec sheets made by RAM retailers.

HP did not make the process easy, but I found the specs, the system was maxed out.'''

I am upgrading a Compaq CQ56-109wm from 2 GB to 4 GB. Finding accurate information has been hard.

I bought two sticks of 2GB PC2-6400 800MHz DDR2 Notebook SODIMM Memory (Part No. MN2048SD2-800), I put it in the system. The BiOS reads it fine, but once it starts loading Windows it either hangs or crashes.

I have gone over the specs, and I don't know what I have missed? Anyone?

It turned out that I was a victim of bad information. Several sites sell RAM gave false specs on the system.

Finally after several attempts, I found the spec sheet on hp's archives. It was already maxed out.