The issue with fast or slow playing MP3 songs is due to the way the MP3 file was originally encoded.
The MP3 player on the LeapPad/LeapPad2 supports MP3 files with sample rates of 44.1, 32, 16 or 8 KHz.
44.1 KHz is the standard CD sample rate. If your MP3 file was encoded with a different sample rate, the playback of the song will be distorted.
Several free media players such as iTunes allow a user to re-encode MP3 files to standard sample rates.
Once an MP3 file has been re-encoded to a standard sample rate, it can be re-synced to the LeapPad/LeapPad2 and it will now play back correctly.