I have the problem with Search function on my server.

I know that this problem is not with asp source code because it is working
on other servers.

On my page user enters the word for search, selects database, selects language
and then clicks on "Submit". First time when he clicks he receives message
"You did not enter any valid characters. Please enter your question again."

And in the input field user can see the word he entered first time. Then
if he clicks on "Submit" second time with the same word he will get correct
results on his question.

I think it can be the problem with settings for Index Server or something
else. Because the same pages with the same source code work correctly on
another servers.

Please advice what should I check on my machine, how I can fix this problem.