SE 7.1 and SCO UNIX V3.2v4.2 problems

I am attempting to run SE on SCO UNIX v3.2.4.2. I have it running on a 486 and am having serious problems. No matter how I configure it, I can never execute more than a very simple query. For example, I can execute the SQL select * from ordersbut NOT select po, customer, orderno from orders It's not just in the select statement that failures occur. Any SELECT INTO of more than 3 columns, and a more that one clause WHERE statement, will fail. dbaccess accepts the SQL query (there are no syntax errors) but in attempting to execute it, fails. The actual error message depends upon the nettype setting in sqlhosts, but is always related to server failure. e.g. with nettype set to setlitcp, I get the message "broken communication bad file number". I have tried setting up sqlhosts nettype as both setlitcp and seipcpip. I've tried all sorts of combinations. Support at Informix can't come up with a solution so far. File permissions are correcly set, as are environment variables. I'd really appreciate some advice on this, or to hear from anyone running SCO and SE 7.1 Thanks, Kate