Today, I got the following error message when browsing to the mySites:
The evaluation version of Microsoft Office SharePoint Server 2007 for this server has expired

Altough i was able to add new sites, site Collections, administrate MOSS and things, this message continued to show up while trying to browse the mySites. I found the following solution:
- Open up the registry editor and find the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office Server\12.0 collection.
- Add read permissions for the WSS_WPG and Full permissions for WSS_ADMIN_WPG.
et voila: problem solved!