After a lot of playing around, registry watching, testing and googling, I’ve finally managed to make a group policy ADM file that can be used to control how Adobe Reader integrates with Internet Explorer.
There are 2 settings in this ADM file (well 3 if you count the fact that one of them is duplicated so that it works for versions 8 and 9 of Adobe Reader) – one is a Computer setting and one is a User setting. The User setting is the one that dictates whether or not PDF documents opened from a web page will open within Internet Explorer or will open in the external Adobe Reader program. The Computer setting is only useful if you have already used the User setting to force PDFs to open in Adobe Reader rather than IE but you want to get rid of the prompt asking users if they want to Open or Save the file each time they click a PDF link.
NOTE THAT AS THESE ARE NOT “TRUE” GROUP POLICY SETTINGS THEN YOU NEED TO DO THE FOLLOWING BEFORE YOU WILL BE ABLE TO SEE THE SETTINGS IN THE GROUP POLICY EDITOR:
Once you have added the ADM files to your GPO, you need to click on the Administrative Templates folder and then go to View -> Filtering -> uncheck the item labelled “only show policy settings that can be fully managed”. Unfortunately you have to do this every time you open the GPO Editor and you have to do it for both the Computer and User sections.
Note: I found I had to restart my test PC before this setting would take effect, so don’t worry if it does not seem to be working straight away after applying the group policy
Here is the ADM file: http://www.cjwdev.co.uk/Other/ADM/AdobeReader.adm
I have found that a couple of machines on our network with Adobe Reader 8 did not respect this setting (seemed to be very random, with some working fine and others ignoring the settings altogether) but all machines with Adobe Reader 9 worked perfectly with this GPO.