Unable to open .acsm file in Digital Editions because it tries to open in Adobe Reader

I have been trying to open Ebooks from my library through Digital Editions, in the past it always worked, but stopped working recently.  I have updated to edition 4.5 but still will not work.  The .acsm file appears to try and open in Adobe Reader, so gets stuck and is unable to open in Digital Editions so I can download to my reader.

Any suggestions?  Thanks.