I have a USB-serial cable connecting my laptop (running 2.6.39 from Debian) to a weather station. My keyboard is connected to a different USB port on the laptop. Whenever the met software is reading and/or writing to the serial port (I haven't yet debugged whether it only happens during read or write), the keyboard badly lags when in X, but not at the console. I don't *think* the mouse is affected, most of the time, unless X is waiting for the keyboard to catch up. I'm apparently using the evdev driver. In xorg.conf, synaptics is configured for the mouse, talking on /dev/psaux, and not as core pointer. corekeyboard and coremouse are left as default. So now, given the bloat (sorry, abstraction) that has been thrown at X/HAL/udev over the last few years, where do I start debugging this one? (friggin give me back XFree86 and a keyboard driver understood by more than 3 people on the damn planet!). Can anyone else reproduce this? You probably don't need a USB-serial converter. It's probably just some conflict reading things from /dev/input/* or in the kernel TTY layer or something, and so any old serial connection busily talking will do it. I think this is only a recent occurence. Being my main desktop, I'm not ready to git bisect it yet, and don't know whether 2.6.39 brought this behaviour in. It could have been back in April: [UPGRADE] xserver-xorg 1:7.6~2 -> 1:7.6+6 [UPGRADE] xserver-xorg-core 2:1.7.7-11 -> 2:1.9.5-1 [UPGRADE] xserver-xorg-input-evdev 1:2.6.0-1 -> 1:2.6.0-2 [UPGRADE] xserver-xorg-input-kbd 1:1.4.0-2 -> 1:1.6.0-1 (god knows why I upgraded. Oh yeah, squeeze. I should have learnt by now). -- Tim Connors