Error Message when attempting to install Adobe Reader 8.0 - Please Help!

Hi,

 

I have downloaded Adobe Reader 8 to install on my Inspiron 9400 running Vista Home Premium.

When clicking on the icon to install (following download to my system), I get a message that reads "Please wait while Adobe Reader 8.0 is being processed. This will take some time depending on your operating system or hardware". This procedure runs its course.  I then get a prompt box asking me if I want to run this file, yet when I respond with "Run" (yes), I get the following alert:-

 

"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".

 

I don't understand?  The Temp folder is not full, neither is my C drive,  I have disabled UAC and I my account has full Administrator controls??  Whats wrong?

 

Any advice and support would be very welcome - thanking you in advance.

 

A.