This problem occurs during uploading an image with PHP script,but only in one computer. Everywhere,where I tested and used my application it works correctly, but only in one computer not.
I can't negotiate change with my provider, there is problem with this one problem computer. I used mozilla and IE.
Thanks for answer.

By computer do you mean you are only having this problem on one server or only on one of your home systems?

I mean home system. Thanx, I discovered the reason of problem. And it was bad internet connection of my client. The server closed the session after one minute uploading picture,because uploading of 2MB picture was very slow (uploading 60kb picture 90 seconds). This is the reason, why it works correctly on all home stations, except one home computer(unfortunatelly client's home computer). Thanks.Michal.

No problem. Glad you figured it out.