As mentioned, "BroadcastMsg" is created in the user's Temp directory when opening a PDF file,could you try rebooting the machine once if you haven't already and check if that helps.
If that doesn't work, check if an update is available for Acrobat using "Check for updates" option under "Help" menu,
Reboot the machine after installing update and try again.
If that doesn't work, try resetting preferences for Acrobat using the steps given in this link: How to reset Acrobat Preference settings to default. reboot the machine after resetting preferences and try again.
Also, let us know dot version of Acrobat and the operating system installed on the machine? You may refer to the steps given in this link on how to check the version in Acrobat: Identify the product and its version for Acrobat and Reader DC
Let us know if you need any help.