I got a commercial app that is working fine on most machines OOB.
I got just 1 user who gets following error when he launches OOB version (note that in his browsers it works fine).

Sorry for russian language, but his machine is in Russian.
Generally it says that there is an error and that silverlight is not installed. I did install latest (5) Silverlight version and it didn't fix the problem.
What could this be?
document.gelElementById(...)? - Tonio