Hello Ram,
At issue is that only the Workstation UI knows about your having requested not to see the message about changing the USB device, but the virtual machine itself does not.
When you start the virtual machine with VixCOM, the dialog still gets generated and the virtual machine waits for an answer. Once you open the virtual machine in the UI, the UI knows you've requested never to see the dialog, and answers it.
There are two ways to get around this, but neither is perfect.
1) Use the launch GUI option. Since the virtual machine gets opened in the UI, the UI will take care of the dialog. For extra hackiness, you could try killing the UI process after some amount of time has passed, if you really need to have the VM running in the background, but there many obvious problems with this.
2) Add
msg.autoAnswer = "TRUE"
to the virtual machine's config file (the .vmx file). This will stop the virtual machine from generating any messages. Obviously, this turns off many potentially useful messages too, but you'll can be sure that the virtual machine won't get stuck in this kind of situation when you are trying to automate it.
Also, check out the "Virtual Machine Automation APIs" forum under the Developer Community section, which is the central discussion for VIX-related matters.
