MySQL selects it's clients carefully?

Environment: Two servers, which another has Windows 2000 Server and another one runs Linux. Both of them has PHP (IIS/Apache) and MySQL installed. They seemingly share configuration and they have exactly the same database structure, data and PHP scripts as well. This combination works in following cases: - Linux PHP application uses Windows's MySQL database - Windows PHP application uses Windows's MySQL database - Linux MySQL client software uses Windows's MySQL database - Windows MySQL client software uses Linux's MySQL database - Either computer's MySQL client software uses MySQL database on the same computer However, if PHP application on either server tries to use MySQL database on the Linux server, it doesn't work. Symptom is quite strange: MySQL connection is established normally, but any simple query fails to run (there is no error, but it returns no result set). I've run all the tests on same user account and this situation is the only one that fails. MySQL version is 3.23.33 and PHP version 4.0.4pl1. Any ideas?