HELP!!! Wierd CF 9.02 issue when "to many" form fields are posted in "post" method

So we just installed cf9.02 64 bit on all brand new windows server 2003 machines and migrated all code over and we have run into the wierdest (and very dead on the water) issue, any form posting to a cf templae with a "large" amount of fields using method = "post"  barfs, works fine with method = "get" or with a smaller amount of fields.  Here are some "basic" examples I pulled out of our app:

https://dev1.mystudentsprogress.com/testposting/smallform.html --> this is using method = "post" and works fine with a small number of fields, click save and it calls a cf template that simply says "index.cfm here"

https://dev1.mystudentsprogress.com/testposting/formget.html ---> this is using method = "get" and also works fine, click save  and it calls a cf template that simply says "index.cfm here"

https://dev1.mystudentsprogress.com/testposting/formpost.html --> this is using method = "post" and it barfs, click save and you get an error 500 page

And once this happens the "next" call for even the succesfull pages returns a blank page i.e. go here:

https://dev1.mystudentsprogress.com/testposting/smallform.html and click save

No go here again and click save:

https://dev1.mystudentsprogress.com/testposting/smallform.html

...there is nothing in any of the CF logs indicating any kind of errors, it just flat barfs on forms with post method and a large amount of fields, clearly a MAJOR issue as our app has lots ot screens with lots of fields!!