Recently I tried using a third party form management tool (FormStack) and couldnt get it to run properly - the page ran reallyn slow and the IE claimed a script was taking too long to respond.
I contacted Formstack support and got the following reply:

"You are using deprecated Javascript in your script.js file which is causing the rollover to not work. One Line 27, you're using document.all.tags which is not a standard function. You will likely want to use document.getElementsByTagName('a') instead of document.all.tags('a'). Chrome will actually display the form when the envelope is rolled over, but is complaining about your use of routeEvent, which also appears to be deprecated.

I was only able to reproduce the issue with clicking on fields in Internet Explorer and according to IE your webpage should be displaying in Quirks mode, suggesting there are other issues with how your page is constructed. I suspect that the "Long running script" error is being caused by your rollover code. I would highly recommend that you use a modern Javascript library such as jQuery or Prototype which has a lot of the functionality provided by your rollover code built-in."

Because script.js comes with NOF10, is there a way to upgrade it without the pain and cost of moving to NOF12 ?