I'm not sure exactly what the cause of the reboot issue, but I may be able to offer a little insight into the driver issue.
Win7 does not natively support USB3, you need drivers for w7 to be able to use a USB3 card, unlike w8 that supports USB3 natively. Note that Paul Pang links to a win7 driver and a win8 driver for his card which is actually the driver for the NEC chipset on the USB card which may well be the same chipset as is on your normal USB3 card. Make sure you load the w7 driver because the w8 driver will probably not work too well.
Sometimes we tend to over-think things so the first thing that I would do is to pull out your normal USB3 card without removing the driver and plonk the PPAstudio card straight in there and see if it is recognised by the o/s. If it is recognised with the existing driver then try to play some music. If it plays music I would then install the correct driver by going into "Device Manager" and finding the Pang card on the hardware list and then update the driver manually. Of course if you have trouble with the new driver then you can simply go back into "Device Manager" and "rollback" the driver to the original one.
Hope this works for you. Let us know how you go.