I can't boot up my notebook

[Llonaid]

I am haveng problems in booting up my notebook, it seems to be stuck in a loop.
I can get so far as the account icons, but when clicking on any of then, I get the usual log on message, which quickly changes to a 'loggong off' and 'Saving your settings' message. This is then followed by the account icons again, and so the loop continues. Please, please can anyone help me to correct this fault?
Many thanks, Llonaid

[MarkRae]

Try booting into safe mode.

Unbelievably, you don't actually say what operating system / version you are using, so it's impossible to advise you further...