My first suggestion would be to upgrade to Protect 7.8 since there have been numerous bug fixes in it. You can download the install from www.shavlik.com/downloads.aspx and install over the top of you existing 7.6 install to upgrade. If the issue persists, the deployment job may be failing at the scheduler level.
For the scheduler: You may want to force the Protect console to reinstall the scheduler on the target machine. On the target machine, open up a command prompt and browse to the folder C:WindowsProPatchesScheduler
Type: stschedex /remove
Then go into a windows explorer and delete the entire C:WindowsProPatches folder and sub folders.
Attempt another deployment.
There are a lot of variables that could be contribution to the deployment issue so contacting support at firstname.lastname@example.org would be a viable option too.