The config and symptoms:

aix 5.1.1 client
added schedmode prompted to dsm.sys

: the client for scheduled backups is put into the background
        in a standard fashion.

: run dsmc from command line and it HANGS. No command can be entered.
        just hangs.

If I take the schedmode prompted line out of the dsm.sys and
start the client in the background, etc. and run the dsmc command
at the command line normally.. ALL WORKS FINE.

any ideas?

Thanks
Tom