Admin translation disapeared since update

Using:
wp trunk + bp 1.2 bleeding
wpmu 2.9.1.1 + BP 1.1.3

I’m expecting some strange issue with 2 install of wp and wpmu both with buddypress and on different servers.
The single install didn’t work anymore with bp since update to 2.9.1 and it shows a blank admin page each time i try to load it with a translation indication in the config.php

I see also fatal errors due to memory limit size (20mb in y case). They all coming from class.simplepie.php, which has to do with mo files…

On the wpmu install, BP is working and no memory errors appearing but it’s impossible to have a translated wpmu admin – only BP is translated. When deactivating BP, all is fine in wpmu… Several other people i konw use 2.9.1 and have same translation lack since latest update.