keyboard to usb adapter

[HEC]

It depends really on the keyboard as it's PS2 type it could be some older model drawing too much power and PS3 might not cope with that as well as your PC. As it's an active adapter is should work correctly. One other option you can try is to put the (powered) USB hub between PS3 and this adapter (or use let's say one built in the monitor if you have such model) etc.