There is nothing that I am aware of in the PC that would cause this. If you follow these steps, I will be able to tell you the problem
1) Install Wireshark on the problem PC
2) In the PLC, create a controller scope tag "DINTTag" of type DINT
3) Start with a new AdvancedHMI solution
4) Add the driver to the MainForm and set the IPAddress
5) Add a BasicLabel to the MainForm
6) Set PLCAddressValue and PLCAddressKeypad to DINTTag
7) Make sure RSLinx is completely shut down
8 Start a Wireshark capture session
9) Run the AdvancedHMI application
10) Click on the BasicLabel and enter the value 99
11) Close the AdvancedHMI application
12) Stop the Wireshark session
13) Save the Wireshark capture and post it here