I am running Ubuntu 11.04 on my Fujitsu Siemens AMILO Pro laptop.
The system clock keeps on falling behind. I set it to the correct time, but it slows down and speeds up sporadically.
Can I fix this? If not, why is it happening?
The clock loosing time is most likely to be caused by a fault CMOS battery. You can work around it by running ntp.
You can do this easily via the clock. Click on the clock and choose the bottom option of "Time & Date Settings..."
You have to "unlock to change these settings" and enter your password.
Near the bottom, where it says "Set the time", choose "Automatically from the internet". If you haven't got ntp installed, doing this will automatically go off and install it, so you may be asked to enter your password again to perform that step.
This will keep the system clock correct, but wont update the hardware clock on the BIOS. If you want to do that, you will need to schedule a job to run hwclock command with the -w or --systohc flag.