Workflow JavaScript errors

I get several JavaScript errors when I use the Workflow with IE8:

• Clicking on Show Graph (IE 8 only)

  Line: 2093
  Error: 'constructor' is null or not an object
  

• Clicking on the Home > Workflow tab
  • IE 8

    Line: 7233
    Error: 'elements' is null or not an object
    

  • IE 9

    Line: 7246
    Error: Unable to get value of the property 'addEventListener': object is null or undefined
    

• Clicking on the Process buttons from the Workflow tab (IE 8 only)

  Line: 1
  Error: Invalid argument.