Guys, I'm hoping someone has heard of this before and knows what's going on. I have two systems with the following characteristics: Code: System 1 "production box": Gigabyte GA-X58-USB3 Core i7-950 24GB of G.SKILL Ripjaws DDR3-1333 Adaptec 1430 SATA HostRAID adapter with WD2500YD (Raid) and WD1001FALS (black, WDTLER-ified) drives, two of each, in mirrors System 2 "test box": Lenovo 7522K6U (Pentium Dual Core E6300) 4GB DDR2-800 Seagate ST3250318AS On both systems: Windows Server 2008R2 SP1 Datacenter Hyper-V role installed File Server role installed The problem appears to be random data corruption when dealing with large files and seems to be related to cache of some sort. Let me cite a 100% reproducible example from the production box. I build a new virtual machine and install it from an ISO file which I have verified has the correct MD5. My ISO files and the VHD are stored on the WD1001FALS drives. For the sake of discussion let's call it a "WZOR 7601 Windows 7 enterprise x64" install media. The machine installs and boots correctly. A few moments later, I build a second new virtual machine, install it from the same ISO file. The install fails citing a corrupt install disk. I check the MD5, it no longer matches. I get that sick feeling of panic. I notice when I run the hashchecker tool it reads the file extremely faster than normal. If I leave it alone and wait an hour or two and check again, the MD5 of the ISO file has magically fixed itself. I have performed the same test on the "test box" and got the same results, which makes me think it is not necessarily hardware related. So far, I don't appear to have lost or corrupted anything permanently, but this has got me really worried. Additional observation: If I put each box through a normal shutdown, all the Hyper-V machines save state, and come back online when the box is turned back on. However, any machine using a very large amount of memory will very likely fail to restore citing a "memory corruption" error. This has only happened on the "production box" and I theorize this is because the "test box" doesn't have a large enough memory to trigger a corrupt save state file.