I recently received my Acer 4520 back from Acer service guys. They took almost 4 months to replace the motherboard!

Anyways coming back to topic. I have Ubuntu 10.10 installed on it. Whenever I try using left or right mouse buttons (on trackpad)there is no response. Even tapping on trackpad yields no output. However the mouse cursor moves when I move my finger. I am pretty perplexed by this behavior. I am unable to pinpoint the fault. I don't know if it is a hardware or some driver issues. Can anyone please help?