An unexpected error has occurred while loading the application plug-ins (Trados Studio 2017)

When I opened my Trados Studio 2017 this morning I received this error message:

I looked for the same error message here at the SDL Community site and tried out the advice of repairing the software but unfortunately nothing happened. I have saved the actual error message which says:

<SDLErrorDetails time="25-02-2017 08:54:45">
<ErrorMessage>An unexpected error has occurred while loading the application plug-ins.</ErrorMessage>
<Exception>
<Type>System.IO.IOException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</Type>
<HelpLink />
<Source>mscorlib</Source>
<HResult>-2146232800</HResult>
<StackTrace><![CDATA[ at System.IO.Directory.DeleteHelper(String fullPath, String userPath, Boolean recursive, Boolean throwOnTopLevelDirectoryNotFound)
at System.IO.Directory.Delete(String fullPath, String userPath, Boolean recursive, Boolean checkHost)
at Sdl.Core.PluginFramework.DefaultPluginLocator.SyncPlugInPackages(String thirdPartyPluginsDirectory, String thirdPartyPluginsPackagesDirectory)
at Sdl.Core.PluginFramework.DefaultPluginLocator.SyncPlugInPackages()
at Sdl.Core.PluginFramework.DefaultPluginLocator.GetPluginDescriptors()
at Sdl.Core.PluginFramework.ValidatingPluginLocator.ValidateThirdPartyPluginDescriptors()
at Sdl.Core.PluginFramework.ValidatingPluginLocator..ctor(IPluginLocator baseLocator)
at Sdl.Desktop.Platform.Implementation.Studio.LoadPlugins(Boolean loadThirdPartyPlugins)]]></StackTrace>
</Exception>
<Environment>
<ProductName>SDL Trados Studio</ProductName>
<ProductVersion>14.0.0.0</ProductVersion>
<EntryAssemblyFileVersion>14.0.5821.4</EntryAssemblyFileVersion>
<OperatingSystem>Microsoft Windows 10 Home</OperatingSystem>
<ServicePack>NULL</ServicePack>
<OperatingSystemLanguage>1030</OperatingSystemLanguage>
<CodePage>1252</CodePage>
<LoggedOnUser>LAPTOP-O963K78I\Bruger</LoggedOnUser>
<DotNetFrameWork>4.0.30319.42000</DotNetFrameWork>
<ComputerName>LAPTOP-O963K78I</ComputerName>
<ConnectedToNetwork>True</ConnectedToNetwork>
<PhysicalMemory>16567276 MB</PhysicalMemory>
</Environment>
</SDLErrorDetails>

In this connection I would like to add that for the last few days I have had some problems with the installation of the plug-in Qualitivity which I have installed  and uninstalled several times. I have even deleted every trace of the plug-in from my computer but it is not possible for me to install it. At my final attempt yesterday I received an error message about JIT-Debugging so I believe that something must be wrong with the plug-in as Trados Studio 2017 was working fine before I tried to install Qualitivity.

 

Can anyone please help me?