[xwiki-users] Registration and Layout settings resetting

Hi, It seems that my wiki is spontaneously resetting several configuration settings, most notably the registration, email, and layout settings. I enter information like the email server, address, and port, which panels to display in the sidebar, or whether to require email verification. After a few hours, I return to the site to find that the panels are turned off, email registration is turned off and the boxes for formatting verification emails, etc are blank, and half of the email settings are cleared. There may also be other configuration options being reset that I haven't found yet. I am the only administrative user on the wiki. It's also definitely not due to vandalism - exactly the same settings disappear every time, and it has now repeated itself 4 times in the last 24 hours. I'm running XEM 4.2m2 on Tomcat with MySQL. Any help would be greatly appreciated... thanks, Aaron