ver. 2.5.0/ 2.5.1 image uploader still doesnt work :(

Hello, I had today problems with uploading images – I made that first time after changing version to 2.5.0
I found, Im not only one and solution is ver. 2.5.1
After changing version (more than once) I have still not usable uploader. After reading with usage all advices here: http://wordpress.org/support/topic/164999
also with removing flash uploader!!! – situation is the same.

Uploader doesent upload files to server – uploaded files R not on the server physically after uploading them, but wordpress uses propper dimensions of the uploaded file in post, but without thumbnail (I have “lost pic” win icon) and the same in the Library – all old files R presented correctly, newest not.
I told with my server operator and nothing – he said, problem is cos double “/” which script loaded by script to the path after word “upload”, but Im not sure, – all old adresses have the same double sign in that place.

After use of non-flash-uploader plugin I have only one new – I have two buttons in the window of the pic to upload (find, upload) – before was only one (select files)and behaviour of the uploader was start uploading immediately after selection the file.

Any help?
It’s my first problem with WP since many years… BTW. idea of flash uploading is looking nice but in practice is not good I think (flash is my business)