nissan almera radio/cd gets very hot and stops taking cd?

my car radio/cd plays cds and suddenly when you change the cd it does not want to play anymore and it gets very hot inside one can feel it when the cd spits out. the other strange thing it does is not want to play original artist cd but yet it will play for eg bump no 22 or best of sokkies but not for eg kurt darren or nicholas louw original artist cd. it this just co-incidence.
it always gives error code 7 what can that mean?