Hi, I faced the same problem: Here is how I got on top of it: 1. On Windows 10: Click on MS icon on left corner of the task bar (4 rectangles or windows sign) 2. Right click > Control panel > Control Panel\Programs\Default Programs\Set Associations 3. Sort by Description (Other available options are Name, Current Default) 4. You will notice that the (Adobe Acrobat Document) PDF files have been associated with Chrome html or other similar file types like firefox etc 5. Click any one file name which is the 'errant file type' 6. Click on the Change Program button which will open a fresh Dialogue box 7. Say OK, Save, and exit. 8. Wait for 15-20 secs, (could be longer if you have many many files to be reset). 9. Go back and open any file which was previously acting funny and Voila! it is all set and you are back to the normal world! ... View more