>>In VFP 6 it will not hang up server. Take a look to the SYS(2335) function.
>>If unattended mode is enabled, it will throw error #2031 User-interface operation not allowed at this time. That is why I suggested that this workaround might be used in your case.
>
>Under WWC, if I access a table which is not opened, the server will wait for someone to open a table. Do you know if the SYS(2335) is enabled under WWC?

It is depended on the way you build application for WWC. There are 2 modes. 1 is when your EXE application runs constantly and waits for requests. In such case dialog box is possible. You can try to workaround this by putting KEYBOARD "{ESC}" and keep that Escape code in keyboard buffer all the time, so when dialog box appear it is immediately closed. Second mode is when your application is built as a COM server called by WWC. In such case you can use th unattended mode and forget about any hang ups by dialog boxes, messageboxes or other things in developers code.