Fix for Adobe Acrobat XI Pro Error “Failed to send a DDE command”

Adobe Acrobat XI Pro v11.0.19 would instantly crash when opening .pdf files and show the following error message:

Failed to send a DDE command

Issue seemed to be that Acrobat was already running another process which had crashed so after killing all Acro* processes it worked like usual again.

However, fast forward a few minutes and Acrobat started hanging again. We tried to do a repair install from the application list (appwiz.cpl) but it got stuck.

Finally we rebooted the computer… problem solved.