ExportImage, hi res, nothing happens

Hello,
I found several Threads on my Problem, but none containing a solution.
The problem is, on my machine at least, that when applied to larger scaled matrices, nothing happens on the "exportimage" message, regardless what filetype used.
i didn't try out all the different formats, but for sure is, that it does work fine with 3000 × 1687, and does not with 5000*2812 pixels. simply nothing happens. that means that the dialog box comes up, but there is no file created after saving. Writing the content of the matrix as jxf works fine too.

all the other Threads seem to indicate, that it always seemed to be not reproduceable on other machines, but the amount of threads on the problem on the other hand seems to tell it's a considerably spread problem.

Does anybody know something about this?
Any solutions?
Is the Problem maybe solved, and it really is just my machine?
Thank you a lot,
woyteg