I never used one of those, but maybe your not sapost to beable to access it untill you install Drivers that may have come with it?
Or simply try plugging it into a different usb port.
Or if none of that applys or doesnt work... you can try this...
go to /start/run/ type 'cmd' hit Enter
type 'Set devmgr_show_nonpresent_devices=1' hit Enter
type 'Devmgmt.msc' hit Enter
then once Devmgmt opens (aka device manager), go to "/view/Show hidden Devices"
then right click and uninstall all instancess of the mini-dvr. (note- Dont mess around with most of those hidden devices, there hidden fora reason)
then reboot and plug the mini-dvr back into the usb port and see if it works that time.