To isolate the VM's virtual clock from the physical host system's clock, you will first need to add these entries to a virtual machine's associated .vmx configuration file while the VM is powered off:
tools.syncTime = "FALSE"
time.synchronize.continue = "FALSE"
time.synchronize.restore = "FALSE"
time.synchronize.resume.disk = "FALSE"
time.synchronize.shrink = "FALSE"
time.synchronize.tools.startup = "FALSE"
To make the changes, navigate to the folder containing the virtual machine's configuration file and open the configuration (.vmx) file using a text editor such as Notepad. Once you have added the lines shown above, save the .vmx file. Note that the line tools.syncTime may already be present in the .vmx file, so you will just need to make sure that it is set to False. The lines starting with time.synchronize.continue should be added after the tools.syncTime line. For more information on VMware time synchronization, the document "Time Keeping in VMware Virtual Machines" is a very good read.
With these entries in the VM's .vmx file, each time you create a snapshot of the VM, the date and time of the VM's virtual clock will be preserved. So if you need to use the VM a week later and revert to the previous snapshot, the VM will resume running and with its system clock set to the date and time of the snapshot. Tech Help—Just An
You can force the VM's virtual clock to start at a pre-set time (such as one minute after the date/time stamp on the VM's virtual hard disk file) by adding the rtc.startTime value to the VM's .vmx configuration file. When present, the value associated with rtc.startTime sets the VM's clock to a specified Unix timestamp. For example, to make a VM think the date is Jan. 2, 2007 and the time is 4:24 p.m. Eastern time (GMT -5), you enter the following in the .vmx file:
rtc.startTime = 1167773040
If you're from this planet (not like me) and can't convert current times to Unix timestamps in your head (like me), try using the online Unix Timestamp Converter http://www.4webhelp.net/us/timestamp.php
Keep in mind that if you add the rtc.startTime value, you also need to add the lines (listed earlier) to disable time synchronization to the .vmx file as well.