SightMax 7.1 - Browsing the SightMaxWebServices.svc can show the error:
"error occurred creating the configuration section handler for could not load type system.security.authentication.extendedprotection.configuration..."
It seems that if you remove KB976769v2 update, it fixes the problem. You can find it under Add/Remove Programs under "Microsoft .NET Framework 3.0 Service Pack 2". Don't forget to check "Show Updates" at the top first.
After removing it, Automatic Updates (if enabled) may ask you to install KB979909 and/or KB982168. I'd recommend ignoring these for now until a hotpatch or fix is available, especially as this is just a temporary fix.