I ran into a problem somewhat like this after installing Demona -- her head morph was set to 100% by default on all G8F and G8.1F characters everywhere, which deformed a lot of my pre-existing characters. So my guess is you installed something for G8M/G8.1M with a similar issue.
There's probably some way to fix the product itself to not do that, but I haven't found it yet. For now all I did was delete the files from the offending package and that fixed the issue.