Digital BW, The Print

I have been using QTR and the QTRgui quite frequently lately but now all 
of a sudden I get an "Invalid floating point operation" error each time 
I start up QTRgui (v 2.1.2).
I can't drag and drop images from Thumbsplus on it anymore like I used 
to do but I still can get a print when I select an image via the Image menu.
Also, it no longer remembers the settings for blend & ink limit 
adjustment like it used to.

How can I get it back to normal?

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Hans VR
www.vanrafelghem.com