Arduino IDE problem

I can't get the IDE to work on my Ubuntu 10.04 it worked fine on 8.04. It opens up fine but as soon as I try and use it, it locks up and I have to force quit to close it.

HELP I'm having Arduino withdrawal.... :-/

Ok I fixed the problem only to get a new one! Now when I try and upload i get this error

avrdude: stk500_rec(): programmer not responding

I'm using Ubuntu 10.04 with Arduino 0021 with Seeeduino Mega which uses avr mega1280.
I have the board settings at Arduino Mega(ATmega1280) and Serial set to dev/tty/usb0

Please help! :-?