1. /home/agladwin/.kde/share/apps/Kmail/lock is a lock-file. To clear this issue, you should first verify that PID 4781 is not a running instance of KMail using
. If it is then it has likely crashed; in this case you may want to kill it with
The reason you cannot find the file (I suspect) is that .kde is a hidden directory (as it starts with a dot); rather than browsing for it in a GUI tool it's faster to delete it from the command-line:
2. I can find no reference to such an error message off hand. What version of KMail are you using?
An inability to receive email is usually caused by incorrect settings; you need a POP or IMAP connection to a mail server, specifying the correct server, port, protocol, authentication method, username and password. Your ISP should be able to supply you with this information if you are unsure.