We have moved our Exchange data and log file to seperate disks and I was going to remove the old common disk as nothing should have been using it. However after removing the disk and rebooting neither of Public folder or Mailbox store would mount. After I added the old disk back I was able to mount both fine? I used File Monitor to observe disk access and found the Microsoft Exchange Information Store service is access E:\Temp a couple times a second looking for something, but there is no such file. There are 2 GUIDs listed, I assued one for the Mailbox store and one for the Public folders. I tried reseting HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\Schema\<MDBGUID> to 0 for both and rebooting to try and refresh the Schema but the GUID remain the same and continue to try accessing the E:\Temp location with the same NO SUCH FILE error.