Corbett,
I suspect all your problems are related to permission or ownership problems. You installed 1.0b5 on top of an earlier installation didn't you? Earlier versions weren't quite as strict on perm/ownership (esp. group ownership) as 1.0b5 -- but they had other problems. BTW, you followed the README note about moving your list template files right?
Please look at your installed directory (e.g. $prefix). You want to make sure all the files are group owned by the `mailman' group, and that all directories and files are writeable by group. Further, be sure that all directories have the group sticky bit set (so new files will inherit the right group owner).
You want to in particular, make sure lists/yourlist/config.db is group writeable, etc.
If all that looks okay, but still doesn't work, then I might suggest trying to re-install Mailman 1.0b5 into a fresh location. Re-run configure with a different --prefix. Once you've done the new install, try creating a test list under the new location (you might need to set up your Web server to include a second ScriptAlias). If this test list works, then you should be able to copy your existing list subdirs to the new location (again, watching very carefully group write permission and ownership). Now your old lists should work from your new URLs.
-Barry