Can't choose different drive for cache

I'm using Adobe Master Suite 6 on a Windows 7, 64 bit system.

Upon opening the program, I received a warning about cache getting too full.

I went under preferences to choose one of my other hard drives, but I'm not able to navigate to another hard-drive - only to my desktop or other folders on the default C drive. 

I don't see anywhere that I can simply type in a different drive letter.

Do I need to add a favority with links to another drive?  Or some other way to go from C: to E: ?

Thanks