problem in Vista 64-bit with installation directories

Hi

I am trying to run several installation programmes and notice that I am not seeing all of the root directories in the various hard disks I have on my music PC. The 'default' C directory does not have enough space (3gb remaining) to load all the music samples I want to install, but several other drives do have space. However, they just won't display as 'available' in the directory trees. This only happens with some installation programmes, others see all the drives perfectly.

Is there some reason why some installation programmes will not display some of the disk drive directories in my PC?

thanks for any information or suggestions for curing this problem.


Barry