PC 'a', when connected to a printer (HP970cxi) works perfectly, whilst laptop 'b', when connected directly to the same printer also works perfectly. However, when both are connected to the printer via a switching-box with 'a' and 'b' switch positions neither will work. There must be some signal passing because the printer wakes up and readies itself but then nothing happens. Both box and all cables have been replaced in case they were faulty but the problem remains. My guru, who deals with far more complex problems than this on a daily basis, is stumped on this one. Do any of you super-gurus out there have any suggestions, please?