Two easy things to try.
Windows itself could be the spoiler here.
1.See if System Restore is active on this drive and if so, turn it off. Restart and try again.
System Properties > System Restore Tab
2.Check if the drive is set as a swap drive (pagefile) in Virtual Memory.
System Properties > Advanced Tab > Performance Settings Button >Advanced Tab>VIrtual Memory Change Button. Disable if this drive is chosen. Restart.
Repartition.
Good Luck!