system files damaged

on my nintendo ds when i put my r4 in it has come up screen - system files damaged please reinstall system files, can someone explain how to fix this problem as my daughter is doing my head in please thanks

Um...redownload the firmware?Prehaps she accidently deleted some of the firmware files somehow.

Re-install the firmware. http://www.linfoxdomain.com/nintendo/ds/http://www.linfoxdomain.com/nintendo/ds/?mode=desc&fileid=1786