You may want to add 'noacpi' and 'noapic' to the end of the kernel boot parameters in grub. (VM
Press ESC when at the grub screen, then 'e' to edit the boot entry, then add to the end of the line, press enter when finished, and then 'b' to boot the highlighted entry...
If this works well, make it permanent by appending the same options to the kernel line of the /boot/grub/menu.lst file.
If this does not help, look into running ntpd within the VM, it should constantly compensate for problems like this.
The fixes that DRZ mentioned would also be worth a try, but they are parameters that can only be changed in VMWare ESX I believe, and not the server product.
//TrX