all apps seem to have reset

[Rhyno]

Hi all,
my 9 mth old PB 12" is starting to play up. Mail keeps losing mailboxes and signatures, iCal has lost all of its dates, nothing has happened to address book yet but i'm not sure what to do. The loss of mailboxes is ******** me no end.
Any ideas?

[awulf]

Make sure you have installed the latest free Mac OS X updates (open software update).

If it still continues:

Backup your home folder to another place, and delete your home folder.
Next time you log in Mac OS X will create your home folder again, and copy all essentials from your old home folder such as documents, your address book list and saved e-mails (the last two live in your Library folder).

If problems still continue:

Back up all the data you wan to keep (onto a CD or another Hard Drive), format the Hard Drive and reinstall Mac OS X.