failure and silence of SQL commands

I'm running psql version 8.1.11 on a Linux server from the command line. It
gives me absolutely no feedback from SQL commands and all SQL commands fail,
but the internal psql commands such as /d or /echo all work. I am not
running it in silent mode; the command I use to start it is just the
standard "psql -d database -U user". It tells me that I'm connected, I can
examine the tables, but it won't execute SQL.

Has anyone had similar issues?

Thanks,

John