The Windows (2003 Server) system on which our calendar server (version of NSM.EXE is 4.5.5.1) suffered a fatal drive crash. We were able to resurrect a .db file and a .bak file from within hours of the crash. I'm trying to test the viability of either of these on a Windows XP Pro (SP3) system. If I create a Now Up-to-Date server and "locate" the .db file, then attempt to start it, the log file reports "Server error: Fatal Error: (invalid database ID)." If I try to use the .bak file (after first renaming it to ...db), when I try and start the server, I encounter an unhandled exception: c0000005 at address: 100672ce. I would guess that the original .db file was open during the crash, which caused some level of corruption and this is why the server reports an invalid database ID, but I can't figure out what's wrong with the bak file. Any ideas?