kmail and imap: something stucks

Hi list members, Till last Sunday I used kmail. I collect my mails over imap protocol. But occasionally it took a time to finish looking up. Now it will not finish anymore. :'( This mail to you is written with Mozilla Thunderbird. I have no complains about Thunderbird. So, something is wrong with Kmail. At Sunday kmail couldn't find $HOME/Mail in ~/.kde/share/config/kmailrc due to not finding $HOME and stopped. Still the command "echo $HOME" gives me the right answer. I changed $HOME to /home/<user>. A third problem is that I cannot switch desktop to a second user. Now, these are three problems of which I can't oversee if there is a common disturbing factor. How can I make repairs? Henk