[WriteLog] Error when trying to upgrade to 10.71c

[Gordon LaPoint]

I get the following error when trying to upgrade my 10.70c writelog to 10.71c, 
on Win VISTA, using normal login or logging into ADMINISTRATOR:
Sourcefile not found: E:\temp\WlFull01.cab  (Note: the path varies with how I 
try to run the upgrade, the filename is the same)

I am able to use the same upgrade file on WinXP and 2000 systems without error.

What am I doing wrong on the Vista system?
The install 0f 10.70c went fine and runs fine.

Thanks!

Gordon - N1MGO