VMWare Server / Player failing to start after a kernel upgrade is a common problem, specially in Ubuntu 8.04 which recently experienced a number of upgrades to the kernel. The solution to get VMWare Server / Player working again is an easy one just re-run the vmware-config-pl and press enter to choose the default options unless you want to change the configuration.
sudo vmware-config.pl
Remember this command, you will need it in the future.
vmware — Jun 20, 2008