Follow this steps:

If you are using Internet Explorer:

1. Select 'Tools' from menu
2. Choose 'Internet Options'
3. Choose on the 'Security' tab
4. Click 'Custom Level'
5. Find the section labled 'Scripting'
6. Under 'Active Scripting', select 'Enable' and click OK

If you are using Firefox:

1. Select 'Tools' from the menu
2. Select 'Options'
3. Choose 'Content'
4. Check the box next to 'Enable JavaScript' and click OK