MacBook Air / Parallels USB Storage Drive Association Issues I am working with a 13" MacBook Air and G-Drive w/Thunderbolt. I have to utilize Parallels/Windows to run ESRI ArcView. The G-Drive and another Lacie Storage Drive are tied in to my 27" Thunderbolt Display. 

When I unplug the MacBook Air, sometimes when I plug back in, the drive association, in my case T:,  changes to U:, which means my software can't find any of my 700GB of stored files. 

Is there any way to change the Drive association in Windows or Mac or Parallels so that when I unplug my laptop and plug back in Parallels/Windows knows that that drive is the T: Drive, and not to change it to some other Letter?
The behavior belong to Windows, you can try following this method to assign a permanent letter:

https://superuser.com/questions/108186/how-to-assign-permanent-drive-letters-to-removable-usb-hard-drives