Safari adds extra .TXT extension
In Mavericks 10.9.4 using Safari 7.0.5 and (more recently) 7.0.6, when I download a PDF file, Safari adds an extra .txt extension to some file names (not all), causing the files to open in TextEdit instead of Adobe Reader. I have deleted and reinstalled the latest Adobe Reader. I can open the file correctly as a PDF file if I delete the spurious .txt from the end of the file name, but this requires me to change the name of the downloaded file every time it happens. Is there a general fix?
MacBook Pro, OS X Mavericks (10.9.4), Safari 7.0.6