This is an older thread but it is one I used to look for answers so I'll post up my solution. It shows up as a similar thread under the other one so it's still relevant I suppose.
I followed all of this info but still had problems so I thought I'd post another solution. My issues are with a Goflex Home, it maps it's own folders every time but for the USB drive plugged into the back that I use with XBMC for DVD Movies (Backup rips of all my DVD's, no transcoding), TV Shows, and Portable videos. I map directly to each folder in the external drive.
I opened notepad and typed the following, the quotations would be omitted if there were no spaces in the path, but since there are spaces I have to use the quotes. The XXX's is the IP address of the Goflex Home, though I could have just used Goflex Home instead of the IP. The reason I went with the IP address is because if I used Goflex Home, the drives would show up upon reboot/login as unable to connect. When I use the IP address and reboot, the drives always disappear, even though they are set to reconnect at login.
net use M: "\\XXX.XX.X.X\External Drive\FreeAgent 2TB\DVD_Movies"
Then I saved the file to my desktop as "map M.bat"
I repeated the process for two other drives, creating separate files for each, "map V.bat" and "map T.bat".
I moved the files to the root of C: so it'd be easy to find.
I started the task scheduler.
General Tab:
Name: Map Network Drives
Security Options: Selected Run only when user is logged on.
Configure for: Windows 7, Windows Sever 2008 R2
Triggers Tab:
New:
Begin the task: At log on
Settings: Any User
Advanced Settings:
Delay task for: 30 seconds
Actions
New:
Actions: Start a program
Program/script: Browse to C:\map M.bat, Open.
Repeated the last three steps for map V.bat and map T.
Then I clicked "OK", found the task in the list, right clicked and clicked "Run" to test it out.
It works every time. I am not sure if it would work if the mapped drive showed up as disconnected, but when there is no drive showing up at all it fixes the problem.