The problem was with ms hotfix m818803 caused the difference between 1.1.4322.573 and .903 (I unistalled the hotfix and it works fine. I have reported the 'dare i call it a bug' to microsoft) it is to lengthly to go into here but the problem appeared because I had .903 and my isp had .573 - my advice is do not install this hotfix or if anyone does make sure the production server and all development pcs have it (or don't have it) as (by design or otherwise) there is different behavior (and js rendering) between .903 and .573 FYI, I was told that (something like) the .903 hotfix will make it into the upcoming sp1...which hopefully will not break anything...but again...it took 6 months in the real world to show itself but .573 vs .903 are different, I think they both basically work but - as I found - it is possible to write code that works on .903 and not .573 see http://support.microsoft.com/default.aspx?scid=kb;en-us;818803 for details