Following some computer problems I reinstalled Windows 7 and supporting software. Unfortunately, before installing Adobe Reader I attempted to open a PDF file attached to an email. A message appeared asking which program I would like to use to open the file and I selected Microsoft Word. From that point onwards whenever I attempted to open a PDF file it always opened in Word which cannot read PDF files, instead showing an error message. I have now installed Adobe Reader and can open saved PDF files through the Adobe Reader program. However, I still cannot open PDF files attached to email messages as they continue to open in Microsoft Word. It seems that Windows does not recognise that I have installed Adobe Reader and this is a better program to open PDF files. How can I reset the system to open PDF files in Adobe Reader?

The root cause of this problem is likely related to the file association for PDF files. Each file type on your computer (such as PDF, DOC, XLS) are associated with a particular program. This association is how Windows knows which program should be used to open particular types of files. However, Windows does not do any validation that the program can actually properly open that file – this would be quite a difficult task since Windows doesn’t really know what each program does, and trusts that the file association is correct. When you originally attempted to open a PDF file on your computer (when Adobe Reader was not installed) Windows did not know which program should be used to open PDF files as there would have been no file association (since Windows did not have a PDF reading capable program installed at the time) and thus asked which program should be used. When you selected Microsoft Word it was assumed that this program was capable of opening PDF files and therefore associated the PDF file format with Word so that these types of files would open in Word on all future occasions.

Now that we have got the technical explanation for the issue out of the way let’s move onto the more pressing matter – how to fix the problem! Fortunately this is relatively straight-forward as you now have Adobe Reader installed. Save a PDF file to your computer in an easy to access location, such as the Windows desktop. Right-click on the file and select “Open with” in the context menu that appears. An “Open with” window will appear showing you a list of “Recommended Programs” that can be used to open PDF files. If Adobe Reader is listed under “Recommended Programs” then select the entry, make sure that you tick the “Always use the selected program to open this kind of file”, and then click the OK button. However, most likely Adobe Reader will not be listed under the “Recommended Programs” so you will instead need to look through the “Other Programs”. Click the disclosure indicator (down arrow) on the far right-hand side of the “Other Programs” heading to expand that section and display all of the programs. From this list find “Adobe Reader”, tick the “Always use the selected program to open this kind of file”, and then click the OK button. Now all PDF files in the future should open using Adobe Reader as we have changed the file association for PDF files to point towards that application. There is an off-chance that Adobe Reader may not appear in the list of “Other Programs” either. This would be quite strange but possible, considering that Adobe Reader should have commandeered the PDF file association when it was installed. If you cannot find Adobe Reader then you will need to manually specify the program file. Click the “Browse” button and navigate to the location of the Adobe Reader program. This is normally located in C:\Program Files\Adobe\Reader directory, although this may differ depending on the version of Adobe Reader installed on your system and whether you manually specified a different path during installation. In any case, once you have found the correct directory and selected the program file, follow the same steps as above – selecting that program in the listing and then ticking the box to always use that program and click OK to update the file association.