Right , i have had bag slots do this, not an entire guild bank however.
To reply to Redstar, there was a memory leak and I surmised it could be connected, but with no concrete evidence i am not going to back that claim. Hopefully wow security will put the pieces together.
Initially I thought it may be somebody who bought a signature from me to start my guild, but this does not seem to be the case either. My alt guilds are ok , but the guild my main is on got hammered and I dont think anyone subbed in that guild this year, So that fact helps nothing.
But I want to tell the WOW devs , about the only thing we probably could not replace is like Ungoro Soil or core leather etc. and that stuff is pretty well worthless now anyway,so I am not full panic mode, running headless chicken , hands in the air yet.