R – edit the advanced-cache.php and change the file so it tries to load “mu-plugins/wp-super-cache/”… rather than the directories that are there. It just occured to me that it’s trying to load a non existant file in plugins/wp-super-cache/. I’ll get it fixed eventually.

Sirius – I didn’t realise you were suggesting a timer check. You could simply try deleting the cache from the backend and timing it manually too. If it takes more than 5 or 10 seconds that’s too long IMO.