Can't boot from USB Anymore

[Flats]

I have knoppix 7 running from USB been fine for a week now when I boot up I get to INIT: Entering runlevel: 5 then the root@Microknoppix: prompt. Usually the gui starts up here but all I get is the audio and it skips or stutters and never stops? Any ideas

[Capricorny]

Create a new USB. If that works, you can try refreshing the old one.
One thing here: If you have set up persistent store, and created a (compressed) backup-copy of it (the knoppix-data.img file), you could restore the system to exactly what it was at backup time.