Does somebody have problems while using an usb keyboard and mouse?

I'm not sure how to describe the behaviour, but it's fairly annoying me. If I type fast or using any kind of multiple-key-shortcut serveral keystrokes get lost. It's not repeatable by typing the same, but it's defently not the users fault
Same story while using the mouse. From time to time a click event gets lost.

I've searched the forums and some people had the same problems but no one since snow leopard. According to some solution tips i've disabled usb legacy in the bios, without any change. (changed USB ports as well)

Not sure if it's a problem of my machine or settings...

thank you in advance!