Hello. Thanks for helping me. About test before buy i could say that when i bought joomsef it was version 3.8.2 and everything was fine. The problem occurred after upgrading to version 3.9.2 moreover i started experiencing trouble with virtuemart extension - process of checkout didn't work. I solved it to set $allowUTF = "1"; Now i try optimize my site and it is very inconveniently every time to connect via FTP and manually editing configuration.php . My provider is using PHP v5.2.10 and certainly i tried to use MOZZILLA, IE9, Opera browsers but without effect. Also i turned on show PHP errors on web server but nothing to found.
Do you have any ideas to help me?

Maybe there was some problem during upgrade. Download the JoomSEF installation package using your download ID at www.artio.net/e-shop/download-area and try reinstalling it - open the Upgrade page in JoomSEF and there manually select the downloaded package. That way only the JoomSEF files will be overwritten and all your configuration and SEF URLs will be preserved.