problems playing back mp3's on my alpine!!!! any help please.....

hi all
i've just started to embrace this whole mp3 thing in the car but i'm not having much luck!
i have been ripping the mp3's from cd's in windows media player, then burning them back to cdr's as data files.
when i put the cd in my head unit the files are there as you can see the folders but when you scroll through each folder says "protect". i've looked in the manual of the alpine and it seems that everything is set up ok. i could be wrong though...!
i gave the disk to a mate that had no problem playing the mp3's back on his pc. i don't think that every cd i have converted to mp3 would have a writing protection in or my mate could not play them back.

WHAT AM I DOING WRONG?

my head unit is an alpine CDA-9851
any help appreciated, thanks guys

thanks for the quick response, i'll give it a go.......

i see your point, being a photographer i have an 80 gig back up photo storer + card reader which doubles up as my mp3 player. if i could control this through my head unit i'd be laughing.
if i had an ipod or needed one for any other reason i'd go with the ipod in the car.
been looking round at the in car dvd's, i still may go this route......

got a techie question for you guys.... i'm running a 6 channel denon dca-800 amp. it's been with me for some years, i really rate this amp even though it's pretty old!
do you think i may have problems if i uprate the head unit preouts to 5 volt? i think this amp was made when headunit preouts didn't exeed 2v.....
any thoughts?