If you can recall the annoying clock problem on N73/N80, or if your phone is still suffering from this issue, I found a solution that could work for most of people. The problem basically is, whenever your phone is switched off, it loses time and date, so you have to reset them on each phone restart.

The only solution I've found is to set the Network operator time to Auto-update. You can do this by going to menu, clock, scroll down until you find Network operator time, and change it to Auto-update. After that, whenever you restart your phone, it will prompt you to set the time and date, just hit ok without setting anything, wait for about half a minute, you'll find the time and date automatically set. This worked on my N80, firm V 5.0719.0.2 on Vodafone Egypt. I hope it works for everyone too.