I really dont have a clue whats wrong with your system, 2things you can check
1st. move the .aMule folder from your homedir, to .aMule2
mv .aMule .aMule2
and restart amule with clean settings, and maybe dotn change the temp and incomming folder right away,
connect to teh network, seach for knoppix and start 2-3 different versions and see if that works
2nd. try run amule as root for testing purpose, and see if that works, but just for test. if it works as root, there is some problem with your setting for the user
stefanero
PS: what type of partition is it you are trying to write on? vfat?