My mail reader (pine, mutt, ...) hangs on opening INBOX

This happens because of the precautions mail readers take to avoid losing your mail. Your mailbox is a file, and it is generally a bad idea to have two programs modifying the same file at the same time, as this could corrupt the file. So programs which allow you to alter your mailbox put a ``lock'' on it to ensure that no other program can be altering it at the same time. Unfortunately, sometimes the operating system gets confused and thinks that your mailbox is ``locked'' when it isn't - for example if a mail reader program crashes it will not unlock your mailbox.

To clear up the problem, take the following steps:

1. Change to the mail spool directory by typing ``cd /var/spool/mail''.
2. List all files having your username as part of their names by typing ``ls -l *username*'' replacing ``username'' with your username.
3. The files listed in the previous step will include a file whose name is the same as your username; that is your mailbox. The other files will have ``lock'' somewhere in their names; these are lock files. Delete the lock files and rename your mailbox.
4. Enter and exit your mail reader program.
5. Rename your mailbox back to its original name, and try to start your mail program again. If this doesn't work let me know.