Changed Dept Dimension Hierarchy, erased all historical data!

Yesterday I made a change to our Department dimension. I changed a base level member (034) to be a "child" to another base-level member (050). I changed the Parent property for 034 to 050 and didn't make any changes to the parent of 050, then saved and processed the Dimension with no problems. We later decided we did not want this to be the structure and changed it back so 034 and 050 were both base level members again. Then I saved and processed the dimension again with no problems.

Now it seems that these changes erased all data for Department 050 for all time periods and all categories! Has anyone else experienced this? If so, do you know a way to correct it? One of our IT people looked at the data tables and the data is not there any more, so we are looking at ways to restore it, but I want to understand why this happened so we can avoid it in the future.

Thanks for any help. FYI, we are on version 7.0.115 for MS in a dual-server environment.