that is a well known problem with IE 11. it should be solved by applying all windows updates to the server, or in some cases that may not solve it, installing .NET 4.5 on the server with all windows updates will solve it.
so I would first make sure the server has all windows updates applied. then if the problem continues I would install .NET 4.5 and then check windows updates again
please also be aware you should not upgrade mojoPortal to the latest version unless you have .NET 4.5 as we have had people reporting problems with our 2.4.0.4 release if they only have .NET 4.