Cufon font getting distorted on scrolling

Hi, I have Cufon working fine apart from one bug i.e. the main navigation menu links font distorts when scrolled down and up again it and hovering over them they jump a pixel a up and looks OK. This issue has been posted on a few forums but without any possible solution! e.g. <[login to view URL]> If you think you will be able tofix this please let me know. Thanks!