There's a known problem with Vista and the Library view.
Go to the View menu and disable the Library.

In the properties of both BearShare and BearStart, set
both to run in XP compatible mode and as an Administrator.

If the date change still has to be done manually, try the regular
BearShare 5.1.0.28 instead and uninstall the adware right away.
The adware uninstaller is in C:\Program Files\VVSN.