Hold left when powering on the player to boot into the sandisk firmware.
Thank you very much!

Had to check the flashmemory on the player for errors so i had to format it. Used the Rockbox Utility to install Rockbox again and now the folders are gone. The only ones showing are the .rockbox and playlist folder. And everytime i dissconnect the player from the usb-cable it says "error can't access the playlist control file".
Well it the control file's not present in the rockbox folder not matter how many times i install Rockbox.
What's wrong? It's a 8GB Sandisk Clip+.
EDIT: OK i have been deleting both Rockbox and the Rockbox bootloader by installing the OF and then reinstalled Rockbox. I get the same thing "Error accessing the playlist control file". I don't have this problem with my two other Sandisks, one 4GB and the other 8GB.
I can confirm i get the same with my other 8GB when i reinstalled with Rockbox Utility 1.4.0 (I previously used an older Rockbox Utility with the other 8GB player). It fails to create the .playlist control file. I haven't tried my 4GB but i suppose it's the same thing there.
I also found my other thread which i actually forgot.
http://forums.rockbox.org/index.php?topic=48321.0