I hat the same error since this morning.

The Application work over 3 years without problem. But our hoster installed a few MS patches last night.

 After deinstalling this patches the error disappears.

So hopefully this help for solving the problem.

Here is the list of the patches which was installed.

Cumulative Security Update for Internet Explorer 11 for Windows Server 2008 R2 for x64-based Systems (KB3104002)
Security Update for Microsoft .NET Framework 3.5.1 on Windows 7 and Windows Server 2008 R2 SP1 for x64-based Systems (KB3099862)
Security Update for Windows Server 2008 R2 x64 Edition (KB3108371)
Security Update for Windows Server 2008 R2 x64 Edition (KB3108381)
Security Update for Windows Server 2008 R2 x64 Edition (KB3108670)
Security Update for Windows Server 2008 R2 x64 Edition (KB3109094)
Security Update for Windows Server 2008 R2 x64 Edition (KB3109103)
Update for Windows Server 2008 R2 x64 Edition (KB3102429)
Update for Windows Server 2008 R2 x64 Edition (KB3112148)
Update for Windows Server 2008 R2 x64 Edition (KB3112343)

But i don't know wich of them is the reason