HELP: Can't make select queries in SE 7.1

I have recently installed SE 7.1. I'm running it under SCO Unix. I can make simple queries but anything complicated results in the server connection being broken. I'm getting extremely frustrated and have never seen anything like this happen. A simple statement such as select x1, x2, x3 order by x4loses the connection. I tried making temporary tables but select into causes the same error for temp tables > 3 columns. Any help would be appreciated.