>Hi,
>
>Is there any way to prevent users to open an already open form twice.
>I made command button disable after open a form. But when the form release this command button does not enable.
>
>Please suggest me. Thanks - Saif

You've gotten a lot of good advice, but I'd suggest that you create a form manager class that does the checking others have suggested.

One thing I'm not clear on is that it seems that you're opening one form from another and don't want the user to be able to do this twice. If this is the case, then the simplest solution is to make the called form modal. This is a standard practice when you need information from the user before proceeding.