Ext. HD drive letter is wrong =/

[Cyaneyed]

Ok last night my music suddenly stopped playing, and I found the reason was that my laptop thought my external HD was plugged in twice. The usual letter for the drive is E. However it also showed G. When I physically disconnected the HD, only the G disappeared. So I thought this was weird, but it was late so I didnt really bother thinking too much, I was going to bed. This mornming I booted up, and tere it is again, only now it comes up as G, and no E is present at all. This is really inconvenient because I have ALOT of data on the external HD which is associated with 'E:/...'. Is there any way to put it back to recognising the drive as E, and is there any way I can avoid this happening again?

Edit - Resolved

[patio]

Right clik My Computer and select Manage...then Disk Management.
Find the drive and right clik it and select "Assign Drive Letter".
Make sure the letter isn't already in use.
Re-boot to make sure the changes have taken effect.