The errors seem to have come from content scanning. Here's what I did that made the errors stop.
Click Start, Programs, McAfee, GroupShield for Exchange, GroupShield for Exchange to launch the GroupShield 7.0 console. Click Policy Manager. Click On-Access and then click Master Policy. Click Corrupt Content and under Actions click Edit. Under Take the following action scroll down and select Allow Through. Click Save and then Apply. Repeat these steps for the On-Demand (Default) Policy. NOTE: If similar error messages are still received after making these changes, it may be necessary to modify the Protected Content and Encrypted Content settings for the On-Access and On-Demand policies.
I removed Alert manager from the same server. I was running Alert Manager and Groupshield 7 on the same server and they do not play well together. Uninstall Alert Manager and put it on a different machine and your errors should go away!