As reported in my AccessExtra post Access 2007 Bug Alert: Compact and Repair Might Delete Your Database last week, Access KB Article 950812 describes a scenario where a compact and repair in Access 2007 deletes the database. You can’t download the fix directly but can get it by calling MS Customer Service. This fix will be included in SP2 when that ships.
Backup Before Compact is a free Access 2007 Add-In that I have developed that automatically closes Access to unlock the database file, backups, and then compacts & repairs the database before re-opening it in Access 2007. A fail-safe feature renames the original file, which is retained as a temporary redundant backup until the tool is next used on the database.
You can download the Add-in from my Free Access Tools page.