But why i can play these videos in Pinnacle studio 8 or quicktime if this problem is related with the codec?
The codec is the driver wich tells how a file is going to be compressed (encoded), so if you don´t have installed in the system the right codec to decompress (decode) the file the program won´t know how to decode.
Maybe Premiere is not well installed or is not taking note of the codecs in use, this could be a registry problem.
I had some similar problem with media player and divx, even reinstalling the codec didn´t worked so I made a fresh new install of the entire system and the problem was solved