Have you tried a repair of SolidWorks?
If others can and you can't, then perhaps your SW went off the rails somewhere, especially if it's reporting add-in messages (assuming that's accurate).
Dear Mike Roberts
Kindly follow the below steps before SolidWorks installation. Microsoft update (KB3072630) will affect Solidworks software (versions 2011 to 2015).
Temporarily disable the KB3072630 security fix (we do not recommend uninstalling it) by either following steps (a)-(f) below.
a. Click Start, click Run, type "regedit" in the Open box, and then click OK.
b. Locate and click the following subkey in the registry:
Note If this subkey does not exist, create it.
c. In the Edit menu, point to New, and then click DWORD Value.
d. For the DWORD name, type "RemappedElevatedProxiesPolicy", and then press Enter.
e. Right-click RemappedElevatedProxiesPolicy, and then click Modify.
f. In the Value data box, type 1, and then click OK.
Install, update or uninstall SOLIDWORKS in the normal way.
After SOLIDWORKS installs or updates successfully, reset the RemappedElevatedProxiesPolicy DWORD value to 0 to re-enable the security fix
for KB 307263
For your information refer the link : http://www.solidworks.com/sw/support/techkb3072630.htm
Symptoms Of KB Issue Where:
1. Missing add-ins from the SOLIDWORKS add-ins list in the Tools menu.
2. Error when launching SOLIDWORKS or opening a file: "Could not load SOLIDWORKS DLL:
3. Crashes when recording, playing or editing a SOLIDWORKS Macro.
4. Instability when using Equations.
5. Error when launching SOLIDWORKS or SOLIDWORKS Explorer: "DWG document manager library
is invalid or missing".
6. Pack and go issue
SOLIDWORKS 2011 - 2015 Sp4.0.
Thanks and Regards
E G S Computers India Pvt. Ltd.