This file is a placeholder for the default.ida file.  
default.ida serves no purpose on a unux box, but it
is here because the Code Red worm scans for Windows 
machines with a default.ida.  The result is many 404 
errors in the error logs.  This file is here to prevent 
those 404 errors from filling up the logs.

Other than the 404 errors that may result there is no 
harm in removing this file.