Can't start exe from PDF due to 'not allowed by system admin', but admin didn't change anything

I have created a document with a set of instructions for a workflow. The user should be able to start several applications (all known to be safe) by clicking hyperlinks in the document. This works fine in Word, but from the PDF it returns an Acrobat Reader error (translated from dutch): This file was set to be started by this PDF-file. This is not allowed by the system administrator.

Some paths are local paths (C:/Program Files), while some others are UNC server paths. If the user copies the hyperlink into explorer, the application starts just fine. Therefor it must be an error from within Acrobat Reader. I believe it worked fine a few weeks ago, but somehow this error came up since the last 2 to 4 weeks.

Has anyone experienced this issue, and have you been able to correct it? We would like to allow the user to start a trusted application from the PDF file