I recently updated to 0.9.9 and this started happening to me as well. If a document I'm combining with others has more than one page, whichever document it is (first, second, last, etc.), after the first page, a blank page prints, then a page with this error message:
ERROR: undefined
OFFENDING COMMAND: get
STACK:
/0
-dictionary
I did not have this problem with my previous version of PDFCreator. What should we be looking for in the MergePDFFiles.vbs file that might help?