@Ant
Delete your:
DH0:Prefs/Env-Archive/Sys/wbpattern.prefs
file or similair, I say similar because I am not sure if the paths or names are the same... I am looking at my OS4.1 directories on my SAM etc reset your Amiga once you've done this!
This should restore the default then select another and save? if the same thing happens again, there must be some quirkiness somewhere else
You could just type this very thing into a shell
delete DH0:Prefs/Env-Archive/Sys/wbpattern.prefs
if it says file or whatever does not exist then there are other paths or file
names you need to identify... if it returns to the next line without any
feedback... the file has been destroyed ;-) LOL simply reset the Amiga and
there you go...