Error message while trying to open a document as a Single File.

Hi, 

The OK button won't work, after I have selected the language pair to open the PDF file for translation.  So, I was forced a not add the language pair, so I could move on with the translation, but it won't save any segment when I use the CTRL + ENTER keys. I got the following message: "Object reference not set as instance of an object". Now, my translation is stuck in Trados, and I have no idea how to save it in SLDXLIff. Very frustrated at this point.