Conditions in which xwiki could 'reset' it's content??

Hello, we are planning to use xwiki as our enterprise wiki. While in test period, we configured xwiki with a few spaces. Due to lack of time, it was running but not used for a few weeks. During that period, we did several tomcat shutdown/restart, and sometimes we had to kill the jvm (because another webapp was too hungry in terms of memory). Yesterday, to my surprise, i discovered the wiki had lost all it's content (i noticed it because there was no logo anymore and no security config, so it didn't find anymore the attached logo file to the XWikiPreferences page and anonymous had full rights). Going to the database, i saw all documents except the xwiki default ones were removed from table xwikidoc (thought the attachements were still there, but attached to document numbers not existing anymore). So my question is, how can this happens? Is it because the wiki was still configured with the following line commented? #xwiki.store.hibernate.updateschema=0 meaning the xwiki tables are reinitialized at each startup (note i did not notice such behaviour in first days) We can seriously not afford this to happen again in production, so knowledge about this is welcomed! regards, David Delbecq