When I had fresh installation of 0.5, it showed a blank window when I was filling a form. I thought it supposed to be some question about saving passwords. I couldn't see any text, only "Yes" and "No" buttons appeared. OS is Windows 95 OSR2.
Did you upgrade from an older version of K-Meleon? If so, you need to uninstall that first, and make sure to say yes when k-meleon asks if you want to remove existing profiles.