I have one of these also. Although I've not done much in the way of setup it appears to work OKish for me. Maybe you need to fine tune your requirements. You may need to increase the sensitivities and adjust the area being scanned, which you will need to do by login on directly to the unit and not over a network connection.
It could also be the hard drive you have installed, I had an old 40Gb drive laying around so have used that for testing and it doesn't couple well. Ordered a bigger faster drive, so will see if that changes things any.
Cheers
Garry