Able to download to plc from one PC but not another

[sanchezplc96 0]

We have two computers and a plc that we use for training purposes to teach new techs the basics of going online with a plc and simple troubleshooting techniques. For some reason a couple classes ago we started getting an error from one of the pc's when we would try and download a program to our teaching plc. The exact same .ACD file can be downloaded to the plc with no issues from pc-1 but from pc-2 it gives the error attached below. I tried uninstalling all Rockwell related software from pc-2 and reinstalling but this didn't solve anything. Once I download using pc-1, pc-2 is able to go online with the plc and make edits no problem; it is just the downloading of the .ACD file it cannot seem to do.

Processor: 1756-L55 ControlLogix5555
Firmware Version: 16.21
pc-1 OS: Windows 7
pc-2 OS: Windows 7

I'll be happy to include any extra details if needed but my team and I are just at a loss. Just short of formatting pc-2 we have no idea what could be causing this.

Edited 27 Mar 2019 by sanchezplc96
incorrect OS in OP

[gclshortt 51]

http://www.plctalk.net/qanda/showthread.php?t=120012

Answers posted at the above thread.
Regards,
Garry