this is a VERY well know and documented error that adobe has yet to fix.
simply GOOGLE and you will find the fix 10000 times




"Brett" <public_at_cygen_dot_com> wrote in message
news:uNS8yi4OHHA.4104@TK2MSFTNGP06.phx.gbl...
>I just downloaded the latest Adobe Acrobat Reader 8. After it finishes
>processing during installation, I click run and get this popup:
>
> Windows Installer
> The Temp folder is on a drive that is full or is inaccessible. Free up
> space on the drive or verify that you have write permission on the Temp
> folder.
>
> All of my temp environment variables point to my C drive. I'm logged in
> as Administrator and UAC is turned off.
>
> Any ideas?
>
> Thanks,
> Brett
>