This is exactly how it happens for me.
First I uninstall then delete all mamewah and mamewah setup folders. Then install mamewah, run mamewah to test it (it's fine). Then I install mamewah setup, run setup (it adds layout folders). Then without saving any layout I exit to test mamewah again (it's fine). Go back to mamewah setup, make some changes to my layout, save, and exit. Start mamewah and get the invalid property value error.
This error cannot be gotten rid of till I delete the files and layout directory.
I've tried this on three machines (2 with XP, 1 with 98) and I can reproduce the error.
At first I thought it was a version incompatibility, so I did all my layouts and files manually and it works great. But after reading this thread, you have me thinking mamewah setup was supposed to work.
What's going on?