After Virtual Desktop Agent is installed on Microsoft Hyper-V Windows 7 Virtual Machines or VMware ESX Windows 7 Virtual Machines, the devices will be marked with a yellow warning triangle, as displayed in the following screen shots:

USB Root Hub is marked with a yellow warning triangle:

Device status of the USB Root Hub is Code 31, as displayed in the following screen shot:

This occurs because Virtual Desktop Agent installer installs USB Root Hub if it is not already present on the machine.
Note: This is a benign warning and can be removed easily.

To remove the yellow warning triangle of the devices, uninstall the warned USB Root Hub, which is installed by the Virtual Desktop Agent installer. You can uninstall it from Device Manager by right clicking on USB Root Hub and selecting Uninstall, as displayed in the following screen shot:

USB root hub is not required to be installed for Citrix USB redirection feature to work. However, because of some dependencies, currently the Virtual Desktop Agent installer installs the USB Root Hub causing the yellow warning sign to appear.