OK, little digging in sources. The error number is basically Windows'
error code:
b_error::raise(uSvc, "Error (%d) opening database file: %s",
GetLastError(), dbname.c_str());

And 5 == ERROR_ACCESS_DENIED. Voila. The user as I was logged in had
not enough permission to the file.

Problem solved. :)

--
Jiri {x2} Cincura (x2develop.com founder)
http://blog.cincura.net/ | http://www.ID3renamer.com