Horizon View 5.2 - Serial Port In Use

We are rolling out a new VDI environment using Horizon View 5.2.  All VDI OS's are Windows 7 Pro. We have a USB receipt printer that plugs into the thin client and redirects the USB port to use COM2 on the Windows OS.  Our software is telling us that COM1 and COM2 are already in use by the OS.  Any idea what could be using these ports, and if there is any way to free up COM2 so it is available?

Thanks!