I don't know how but all of a sudden there is a CORBA directory in my /etc directory. and CORBA directory contains the X11 directory and the xservers directory. whenever I try "startx" it is giving the error : /etc/X11/X is not executable. But the directory /etc/X11 is now nonexistent. I tried XF86config afresh, that also failed as it could n't find the directory . where has this CORBA come from ?