You don't have permission to save vista in this location.

1) So run "msconfig", go to the Tools tab, scroll down and select "Disable UAC", then click the "Launch" button. After a reboot you should be able to save files to the C:\ folder.

2)  Create new user account and try

3)         Go to computer where the list of drives are.
             Right click on the external drive.
            Click properties.
            Click the security tab.
            You will find a list of names ie...everybody...admin..etc. Find ''to change permissions click edit''
            Click in all those little boxes so you give yourself all the perks as admin.
            Click apply....then it runs a little check...the press ok.
            All is sorted....you are free to store files on your external drive.