Welcome to the Rockbox Technical Forums!
Pamaury: I don't know if this is you doing (I'm guessing it's not), but the undefined instructions/data aborts/prefetch aborts seem to have disappeared last night on my player. I'm running revision 47ea5b5-120612, if that helps.
I'll look into reproducing this later, and post the exact error, with all its magic numbers and everything.
Page created in 0.138 seconds with 17 queries.