ESS destroys Sweave code by save/build autoformating

[mut8]

When I save or evaluate Sweave code, R tries to format my code by inserting 10 blank spaces at the beginning of some lines. beside the fact that it's kind of annoying when somebody's messing around with my code, Sweave chunk delimiters seem not to recognised when <<>>= or @ do not stand at the beginning of the line but follow blank spaces.

btw: thanks for this great package, it's the reason I started using emacs and Sweave.