I can install Windows 7 x86, but not Windows 7 x64, get BSOD MEMORY_MANAG..

I am currently at a co-op at an IT outsourcing company, and I was instructed to install Windows 7 x64 on 5 systems through WDS. The first 4 went fine now on the fifth, I am getting a BSOD while the PE loads up. STOP 0x0000001A (0x0000000000041284, 0xFFFFF8A0004D7001, 0x0000000000000,0 xFFFFF781C0000000)

These computers only have 1GB of RAM, I found out after that you need minimum of 1 GB for 7 64x but the others worked fine. The diffrence between the computers are one in a Optiplex gx520(which worked), and one that is a Optiplex gx620 (which didn’t work). Not much diffrence between the two besides the Processors, one its both pentium D, ones a 830 3.0Ghz and other is 945Ghz. Any ideas??