Are you connecting your 4350(USB) device to a bus-powered hub or a self-powered hub? Please read the following:
USB is a multidrop bus, meaning that multiple devices can be connected to the USB bus at the same time. The user can use hubs to add ports to the USB bus. Hubs have one upstream port, which connects upstream toward the host computer, and multiple downstream ports, which connect downstream toward the end peripherals.
There are two kinds of hubs: bus-powered hubs and self-powered hubs. Bus-powered hubs receive all of their operational power from the USB bus, while self-powered hubs receive their operational power from an external power supply, like an AC/DC converter. The typical hub will support both types of operation - that is, with external power and without.
However, the power available on the downstream ports to end devices is less on a bus-powered hub than on a self-powered hub. While this decreased power is sufficient for some low-power devices, like keyboards and mice, it is not enough power to run all USB devices. The result is that if one attempts to connect a National Instruments USB-based device (DAQPad-6020E, DAQPad-6507/8, NI-4350 for USB, NI-5102 for USB) to a bus-powered hub, the operating system will report an error, saying there is insufficient power to run the device.
Solution : The solution is to supply power to the hub's downstream ports, using a vendor-provided power supply, as specified in the hub vendor's instructions. If there is no option for making a particular hub self-powered, a different hub must be used. Note that USB ports on keyboards - and sometimes monitors - are typically bus-powered. In these cases, a separate, self-powered hub is required. The ports on the back of a computer are, without known exception, always self-powered.
Hey Waldyd, What Dominick is saying is to get a "power hub". Just go search the web for "usb power hub" and you'll find several vendors that sell self-powered hubs. Using this power supply from hub should give your device enough power to compensate.
The PC USB power, if you think about it, is being shared by everything in the computer. Sometimes there is even an internal USB hub sharing this power with other devices. By utilizing an external, dedicated power source for your device, you will get a consistent and more reliable power source. At least, it's much more stable than the computer's USB power
Have you successfully used this 4350 board before, or is it new and this is the first time you are trying to use it? If you had successfully used the board before, it is possible the board was damaged due to electrostatic discharge (A high-voltage, low-current discharge of static electricity that can damage sensitive electronic components. Electrostatic discharge voltage can easily range from 1,000 to 10,000 V.).
You can protect your system by ensuring your circuitry is correctly grounded. Please read the following Knowledge Base: http://digital.ni.com/public.nsf/websearch/862567530005F09C86256522005CD1EF?OpenDocument