This might be something that could help.
http://zone.ni.com/devzone/cda/epd/p/id/5030
Known Issues:
- NI-IMAQ for USB Cameras only supports a single acquisition from one device at a time.
- Launching and closing camera sessions repeatedly will cause a minor memory leak.
- Exiting LabVIEW without closing the session properly will cause a system failure.
- Using an external image display window on a dual-processor machine or hyper-threaded machine may cause the computer to freeze when moving or clicking the external display window
Best of luck to you!