I want to test an app's behaviour during transitions in and out of daylight savings time. I therefore want to be able to set the date and time of a VirtualBox VM, (preferably from the Control Panel applet, but from a batch file is fine) and not have it "corrected" to the host's time for me. I have turned of Internet sync in the guest and that seems to have achieved this, so I wrote a couple of batch files to set the date to a value just prior to the time of transition in and out of daylight savings time.

The VirtualBox guest doesn't seem to recognize the daylight savings changeover date - it just marches on past with no change of time, no message (yes - "Adjust clock for daylight savings" is enabled).

Any ideas?