Here is a procedure that I found that seems to address the same problem I am having. The only problem I have encountered is trying to conform to item 3. I can provide the needed permissions to the batch files and their folder. However I am having some problem with the target files. I have assumed the target files to the the folder(s) in the virtual drives created by Boxcryptor. However under Properties for those folders there is not a "security" option. There is an opportunity to provide UAC permissions under "sharing" but the process will not complete saying the folder "does not exist". Tried mounting as a hard drive and that didn't help either.
Needing to give permission to all users really isn't a viable option - I don't want Guests on my computer to be able to access my personal files. Obviously that is the case if someone is using file encryption!!!!
1) Make sure that the task is set to "configure for Windows Vista or Windows 2008" on the first page of the task properties (under the "general" tab)
2) Make sure that the task is set to "start in" the folder that contains the batch file: open the task properties, click on the "actions" tab, click on the action and then the "edit" button at the bottom. In the "Edit Action" Window there is a field for "start in (optional)" that you set to the path to the batch file.
3) Make sure that the task is running as an account that has explicit "Full access" permissions to all these things: The .bat file itself, the folder containing the .bat file, and the target files/folders that are affected by the .bat script. Inherited permissions didn't seem to work for me.
4) Make sure that the account running the task is a member of the local "administrators" group for this machine
5) Make sure that the task is set to "run whether logged on or not"
6) The Task should run successfully with expected output when you right-click on the task and select "run" If it does that then it will run successfully when you are logged off.