Animation with Iray, problems..

WMII

hi..

i just tested some animations with iray , the problem is that my clothes are starting to flicker.. or u can also compare it with clothes that are effected by very strong wind.. 

I tested the same animation with 3..delight it was no problem.. i tested several light settings.. sun sky.. dome only and dome and scene with a pointlight.. always the same issue ..

oh yes.. and there are also coming body parts trough the clothing .. in my iray animation.. in my 3delight animation not..

Does anyone know whats the problem or how i can fix this?