Please describe in detail what, exactly, happens when you "can not log in" - quote any error messages you see verbatim. Screen shots will suffice. Can you view your email on your providers web mail interface? Are all the messages you tried to delete still there or are they gone?

When a program crashes unexpectedly it often continues to run invisibly in the background. There are various ways to kill those phantom processes, but the easiest is to simply reboot the computer. Have you done that? If so and it's still misbehaving there are other measures to take, but start with that one.