After a few months of re-imaging the machines (which would of course fix the issue) and looking for a more elegant solution, one was finally found by our intern:
- Close all Internet Explorer windows (if any still listed in Task Manager, highlight them and End Task).
- Go to Start --> Run... and enter Regsvr32 /u urlmon.dll then click OK.
- Go back to Start --> Run... and enter Regsvr32 urlmon.dll and click OK again.
regsvr32 /s /u urlmon.dll
regsvr32 /s urlmon.dll