I frequently export layers as png files. I also have been exporting text layers, so the layer have only text in it.
Since very recently, SOMETIMES, not always, it gives me this message and I am not able to export the text layer:
Click image for larger version. 

Name:	Capture.JPG 
Views:	30 
Size:	50.5 KB 
ID:	101792

Today, for now, I cannot export the text layers at all...

Of course, I could save them as non-text layers, but then I cannot change them anymore...
For now, I will duplicate the text-layer, flatten it and export it,... but that is not a solution for long term...

Any ideas where that comes from?