Well, he said it is reading 3 gigs, and that he has four 1 gig sticks, so its reading 3.
If in not mistaking, 32-bit operating systems only support 3GB of ram, so that could be it.
Look online and see if there is a version specifically for 64-bit.
Maybe it does a quick query with the OS at first, then when it goes into detail, it's 32bit-icity stops it from seeing the fill 4096MB?