After a shockingly long time, I have finally upgraded PPG's forum software to the current version of Simple Machines. The reasons it took so long are boring and dumb, the reason I finally forced the issue is easy enough: spam had been ridiculously bad for years and was finally reaching critical levels of intolerability.
Everybody's account has been reset to the new version's default theme, because the old version was quite broken. I have temporarily disabled your ability to change the theme, for simplicity's sake. At some point in the indeterminate future I will work on updating the old theme, as well as the old FWP look, but I make no promises about exactly when that will happen.
In the meantime, hopefully we can all enjoy a more pleasant forum experience.