Something very strange happened to me.

Hello everyone,
Yesterday I was going to finnish a project that I had been working on for quite some time just to get it off my plate. I installed a pressure transducer in a blower pipe so I can display on a panelview the pressure that is in the pipe for troubleshooting purposes. All I did was put 1 rung in that moves the floating value of the analog input and puts it in a "real" tag so I can use it in my panelview. When I accepted, tested and assembled I lost Comms to the processor. Then all heck broke loose. When I lost comms everything else lost comms with this processor. I went to the PLC and everything looked good. I tried to get online at the PLC and couldnt establish comms their in ethernet nor DF1. I put the keyswitch in program mode and it stayed in run mode. I powered the PLC down, left the PLC in program mode and then I could get online through DF1. I had to reload the program in order to get everything back to norm. I did however "AFI" the rung I had put in just to see if that caused the problem. It seemed to have. What I want to know is why putting this rung in caused this PLC to lock up? I am attaching a screenshot of the rung. I made it show the card setup if that helps.

How about addressing conflicts? Might you have more than one device using the same address(tag), whether discrete or in an array/range? Sounds like this sort of conflict.