I converted my Windows 8 Boot Camp partition into a Parallels VM. Periodically throughout the day, the clock will change to a seemingly random time. At 12:50pm this afternoon, my clock changed to 4:50am. I've tried the following configurations: Parallels Sync Guest clock with OSX host: ON Windows VM internet time sync with time.windows.com: ON Parallels Sync Guest clock with OSX host: ON Windows VM internet time sync with time.windows.com: OFF Parallels Sync Guest clock with OSX host: OFF Windows VM internet time sync with time.windows.com: ON Parallels Sync Guest clock with OSX host: OFF Windows VM internet time sync with time.windows.com: OFF All of these configurations result in the same problem. When the problem happens, I open the time settings in the Windows VM and force a sync with time.windows.com and this corrects the problem.
