Can't locate loadable object for module main in @INC

Make sure @INC is set up correctly, in order to find the path in which MyHandler::ModPerl20 is installed (I think what happens is that when Apache recycles some child, the one starting fresh do not have the correct @INC value, hence not finding your module anymore).

Try to add a PerlSwitches -I/your/path/for/myhandler/ in httpd.conf to see if it fixes your problem.

If that changes things, have a look at Adjusting @INC in modperl documentation to see all details.