I ran into this bug yesterday (at the same time as ultifd), but (like everyone else) failed to provide debug logs. I've enabled debug logging now (by adding DebugMode=true to glestuser.ini) so hopefully when it happens again those will be usable. The 3.3.7 installation I am using is an upgrade of 3.3.6 (using the data upgrade package) but my message was not for data of the indian faction missing but data for the '*random*' faction missing. But there is no such faction, so the game should not be looking for its data on the filesystem in the first place.
So my current best bet is that 'glest master', when this error occurred for the indian faction, had indeed corrupt data, and that there is another, not directly related bug, where the game will look for data of a '*random*' faction on the file system but should not.
