After upgrading from CRM 4.0 to CRM 2011 I get javascript errors

We just upgraded to CRM 2011 and whenever we opened the accounts page we were getting a javascript error saying:
"There was an error with this field's customized event.
Field:window
Event:onload
Error:The value of the property 'Form_onload' is null or undefined, not a Function object"

I did not build our original CRM implementation so I'm not familiar with a lot of the JavaScript code in use, so I simply tried to disable the code from executing, and that actually solved the problem I was having.  


To do so:

1. Open the form that has the error by Clicking New to add a new Record
2. Click Customize
3. Click Form
4. Once you do that you should be at this screen:

1. Now you need to click the Form Properties button and you should land at the window on the right
2. I found the offending javascript
3. Clicked Edit
4. Unchecked the Enabled button
5. Clicked Okay, Okay, and then Save and Publish on the Prior window.  

Now go back and try to create a new account and it won't error out anymore.  So something is wrong with the javascript from the old CRM 4.0 system and I'll need to figure out if we need it, and how to fix it if we do.