Hi Ken,

thanks for the reply... so there is a chance we have got it working. The machine having problems seemed to work with the AjaxUploader when clicking the IE compatibility button (they are using IE9)... so on our webpage we added to the header: 

<meta http-equiv="X-UA-Compatible" content ="IE=9"/>

So far, this seems to have fixed the problem, we continue to test. It is strange though as it worked on all other IE9 machines. Although the problem one was Vista. Others were Win7. We already had the latest .dll.

I will let you know if the situation changes, but thanks for your help. Assume fixed for now.

all the best

James