There’s a Linux kernel problem out there. Canonical has already sent up the update so if you run your Update Manager you should get it and should then reboot.
To double check that you’re running a secured kernel, open up your System Monitor by going to System > Administrator > System Monitor and look for a line close to the top that will say Kernel Linux __________. It should be linux-image-2.6.32-24 or higher if you’re running Ubuntu 10.04.
You can also be thorough and make sure your system wasn’t already compromised by going to the Ksplice site, and downloading their free utility to check. After downloading it, in the terminal go to the directory you downloaded to and enter:
gcc diagnose-2010-3081.c
and then
./a.out
Hope you stay safe!