Sorry, once you create the new year, you cannot post back in 2006. You'll have to go back to a backup and restart the entire process. What transactions are you trying to post back in 2006? Are they relevent? Why not just post them in period #1 of 2007 (since you are now working on 2008)?

Regarding the "version not compatible" message: Did she open 2006 with Ledger V9.0A? If so then the ealier version of Ledger will not be able to open it.

Andrew