Stupid error :(

when i tried installing sony vegas, i get this error. It has happend with another program, but i forgot which one :S
Unable to write to the temp directory in c:\users\ben\appdata\local\temp\.
Check that you have write access to this directory.
annoying as hell, any ideas what it is ?
Answer #1
Do you have enough speed on the C partition? Did you run the program as Administrator? Does the temp directory exist? If that is the case, then do you have write permission to the folder?