If your package is limited to a certain number of hits on the DB side of things or the amount of data, that could result in an error that Moodle really can't trap (ie, capture any detailed info). The hosting provider just rigs it so the data being returned/read from DB simply stops and reports no error for client to view/see.
That is true with the amount of data that might required to restore a course. Moodle 2 does more ... thus requires more.
Strongly suggest contacting your hosting provider and see what they say concerning the DB and your restrictions there (number of hits on the DB, amount of data, etc.).
They, more than likely, if on a shared hosting plan, will recommend you upgrade to a VPS or something similar.
'spirit of sharing', Ken