8.1.7 - advance server linux

Database running in archive log mode.

To stop the archiving without shutting down the DB i executed this command at the system schema user

ALTER SYSTEM ARCHIVE LOG STOP;

system altered.

after this i wanted to check at the SQL prompt connecting as system
to issues this command

select * from v$database;

when i enter username/password it is not getting me sql prompt. i waited for 2 5 minutes but still not getting the sql prompt
what could be the reason.?