Everytime I attempt to Import a package into my scene mono.exe crashes, causing internal compiler errors

Everytime I try to import a package into Unity mono.exe crashes instantly. More specifically I have tried character controller and water(basic). It happens at the stage where the loading bar says compiling script. It will then show an error popup message, mono.exe has stoped working.

Unity was working fine, with the scripts being compiled just fine. If I try to open a script in the project, MonoDevelop opens but does not display the script but just a white box instead.

I have tried uninstalling Unity, Installing the latest update, System Restore but nothing has fixed the issue.

Does anyone have a solution to this problem?