"I/O device error"

what the hell is this ?! i get this everytime i click on the my F drive in My Computer..wich used to says "mpc something.." but now it says "removable disk"..it also says "file is not accesable" when i click on it..ive already been thru 2 compact flash cards ( a 256 mb Sandisk and a PNY) and i get the same thing..ive tried formatting both..both on my MPC and my comp and nothing..is there something wrong with my MPC ?? im getting ready to smash it up against my wall

also whenever i put my card in it crashes both my computer and my mpc..so whats up ?