Vista Problems with Outlook and Word after installing a WD..

I run Vista on my notebook and everything was running well, until I
installed a Western Digital 1TB external drive. I have other WD drives
which do not effect the system.

Now I am getting messages from both Word and Outlook that say "Outlook
could not create the work file, check the temp environment variable"

I have looked online and there are suggestions that the WD software
chages the registry and this is corrected by editing
HKEY_CURRENT_USER\Software
\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders\Cache
registry key and pointing it to %USERPROFILE%\Local Settings\Temporary
Internet Files).

I have looked at this and both of these reistry entries are still
pointed to
%USERPROFILE%

If I boot the computer without the WD drive it works fine but if I then
install the drive Word and Outlook go back to giving the message
"Outlook could not create the work file, check the temp environment
variable" Unplugging the drive does not help but a reboot does.

I have contacted Western Digital and they deny it is anything to do with
their drive. Strange that!! as posts over a few years all point to WD
being the problem. I would have thought that they would have solved it
by now.

Any suggestions appreciated.

what if if got the wd drive connected, then

what is the drive letter for the WD Drive?

open IE
click the tools, options, and look for the the settings button around
browsing history

click that settings button, and check if the temp internet file folder still
the same as you had the Wd drive disconnected?
go to command prompt, type in
set t
the the temp and tmp variables pointing to the right places?