I am also receiving this message but there is no way to exit out of it.  I've hit the RETRY button up to 102 times and then I receive a SEND ERROR message on the file I'm trying to transmit.  No way to exit out of the message unless I do a hard reboot on my computer.  But I'm still unable to transmit files!!  Does anybody from ProSeries monitor these complaints?  

Last year, I had the random program crash and now this year unable to transmit.  ProSeries is going to lose a long-time customer if this isn't resolved.