I'm having a weird issue that I hope someone can help me with. I am running build 7100 of Windows 7 64 Bit. Yesterday I upgraded my ram from 4gb to 6gb. Now Windows will just lock up solid. (No mouse, can't ALT-Tab-Delete) It just freezes. Everything was working with no issues at all until I added the 2gb stick. It's all the same ram. Model is OCZ PC2 6400 OCZ Technology | Products | Memory | OCZ DDR2 PC2-6400 SLI-Ready Edition 4GB Dual Channel I am using a Biostar TF560 A2+ Motherboard. I am just wondering if maybe I missed something when I installed it. It's just weird that it would work fine with 4gb but not with 6gb. Thanks in advance!