In revision 98 the default name for translation tables was changed: instead of “modeltranslation” it is now “model_translation”. You don’t have to rename your tables, just upgrade to DM revision 102 or later and add a Meta class within your translation model:
class MyModel(models.Model):
[...]
class Translation(multilingual.Translation):
my_field = ...
class Meta:
db_table="my_modeltranslation"
Note that this “class Meta” is inside the inner Translation class.