Not sure if anyone has run into this, but I'll take suggestions for troubleshooting and/or alternative methods.
I have a Windows 2008 server on which I am running several scheduled tasks. One of those tasks is a python script that uses pscp to log into a linux box, checks for new files and if there is anything new, copies them down to a local directory on the C: drive. I've put some logging into the script at key points as well and I'm using
command = 'pscp -pw xxxx name@ip:/ c:\local_dir'
I had the same issue when trying to open an MS Access database on a Linux VM. Running the script at the Windows 7 command prompt worked but running it in Task Scheduler didn't. With Task Scheduler it would find the database and verify it existed but wouldn't return the tables within it.
The solution was to have Task Scheduler run cmd as the Program/Script with the arguments /c python C:\path\to\script.py (under Add arguments (optional)).
I can't tell you why this works but it solved my problem.