The first error appeared when i had installed the program on my usb flash on windows. During the installation from unknown reason, there was an error, something like "error, please format your drive" and i pulled out my usb flash (i think installation was not completed). Than i rebooted in Ubuntu and had seen the error message on boot screen:
Buffer I/O error on dev sdc, logical block 0, async page read
blk_update_request: I/O error, dev sdc, sector 0
Than, if i try mount the flash - appears "Failed to mount" message, and i can't execute information from usb flash. How can i fix this?