FYI..

After installing Classic Server v1.5.2 (and 1.5.3) on a Dell XP SP2
system recently, attempting to connect to a db from isql with the
connect command was giving SQL -902 error followed by
"The system could not find the environment option that was entered"

The TCP/IP LSPs installed in Windows showed one non-standard item:
MCLSP.DLL

This belongs to the McAfee Personal Firewall Privacy Service.
Uninstalling it fixed the problem with connecting to Classic Server.

Details on how to uninstall the McAfee Privacy Service are here:

http://tools.mcafeehelp.com/doc.php?siteid=1&docid=71517&support=ts