Is your clock running way to fast for a guest VirtualBox system? There is a long standing open bug regarding this problem reported. There is a solution available in the means of adding some kernel boot parameters. Edit your grub config file (normally '/boot/grub/menu.lst') and add the following;

divider=10 nolapic_timer clocksource=acpi_pm

after a reboot of your guest, your system time should now run at a normal pace.