Same problem here.
It worked for one download then broke and I can't download the rest of two recent orders (9 more files) that just became available when the hardcopies shipped Monday 2/22/2016.
Since it happened in the minute or so between my first and second files maybe I am the one who broke it <blush>?
I emailed customer service but I don't seem to find any webmaster contact or anything like that for the more "IT/IS" sort of issues.
Windows 7 64-bit
Mozilla Firefox ver 44.0.2
cookies & scripts enabled, popup blockers disabled, and haven't changed anything on this end between working and borken downloads
I've downloaded many tens of pdf's over the last couple years without any trouble.
I have not tried to download one that is not watermarked, I wonder if that would work? EDIT - Tried this on a previously purchased and downloaded item... one that was not previously personalized or watermarked (I recall it going straight to save file when I downloaded it the first time a few days ago)... it now tries to personalize and does the same thing as the rest that I can not download.