Assuming the problem is still the same, can you right click the "ionic.Zip.dll" file and click properties. Click the Security tab and make sure the settings are the same as this. The following should be ticked for allow (I assume you are using Windows 7).
Authenticated Users - Modify, Read & Execute, Read, Write
SYSTEM - Full Control, Modify, Read & Execute, Read, Write
Administrators - Full Control, Modify, Read & Execute, Read, Write
Users - Read & Execute, Read
Sorry it took so long to reply, time goes surprisingly fast. See if that works out for you
Thanks,
Dante557