Hi Guys...asked a similar question back here with no outcome. 1 This time another brand new computer, Win7 Professional, 64Bit with SP 1, 1TB HDD with 2 partitions...one system and an OEM recovery partition. 2 Decide to shrink main system partition to create two equal sized partitions using Win7 Disk Management Tools. 3 Do so...format the new partition and new 'Drive' letter automatically allocated. 4 Place data in new partition, manipulate, create new folders etc....great no problems. 5 Shut computer down...restart next day....partition including drive letter not visible in Explorer...go to disk manager...partition visible but no drive letter and when 'Right Clicked' only option is 'Delete' 6 Delete partition and extend volume back to original....search the Forum and see mention of "great tool"...'MiniTool Partition Wizard...download..try...exactly the same results, just uses a more graphical interface. The big question is Why is this thus?.... am running out of hair.