Thanks for your response. That was my first response and it failed to make a difference. I then tried a number of progressively escalting options up to, and including, reinstalling RoboHelp 8.
The last desperate remedy I tried was to delete my browser's MIME file (Firefox) and this finally resolved the issue. I cannot figure out why this changed in the first place though as the project I am building has consistently displayed pdf files within the browser and the only change that I made was by updating the .dll file. I have not updated it after reinstalling RoboHelp 8.
I will conclude by conceding that it is entirely possible that the .dll fix is unrelated to my browser's pdf opening behavior changing
Thank you for your response. As I described in my response to Peter, I've always been able to view pdf's within the browser up to the point where I updated the .dll file. I won't rule out that some other process caused this change though and nonetheless, I appreciate you taking the time to offer assistance.