The problem is is due to iincompatibilty with Internet Explorer 9 (IE9). 

To counter this problem, please note the following possible remedies:

• Using another browser: you may find it easiest to search the databases using another browser i.e. if your operating system is Windows XP or Vista, you could use these browsers: Internet Explorer 7 or 8.0, or Mozilla Firefox 3.5. Alternatively, if your operating system is Macintosh OS X 10.5 or 10.6, you could search using these browsers: Safari 4.0 or Mozilla Firefox 3.5.
• If you prefer to use IE9: you should be able to get around this problem by clicking on the ‘compatibility view’ icon/button which is located to the immediate right of the web address bar when you’re within Web of Knowledge/Science.If you are unable to see a ‘compatibility view’ icon, you will need to activate it by following these steps:
1. Click on Tools menu
2. Click on Compatibility View Settings
3. Type ‘isiknowledge.com’ in the textbox and click on Add