I commented the registeration line for GemBox Spreedsheet in ASP.NET application. The code worked fine. We ran reports for a week. All of a suddent, when I really did not touch the code and I was working on something else, a collegue told me about this error. I immediatly recognized and fixed the issue by uncommenting the reg line. And it worked.
Why it all of sudden it throw error? I do not know.