X5 Sat Nav playing up

[scully91]

Got an X5 2002, sat nav system is dvd and is "carim" i believe, one day it just wouldnt boot up then when it did i had half a map and then kept crashing, hit or miss whether it boots up or not. I have tried a different disc same problem and tried a dvd cleaner.
What next???? I am told by a sat nav engineer it is not repairable and can only be exchanged at bmw for another expensive system, something probably to do with the mpeg ic or something,
You guys got any ideas?

[cobra_mark]

Check the fan hasn't stoppped and the system overheats