Scripts if not properly or compatible with your system will make hangups. If you can no longer access the anything in your computer system, better reboot it first. Afterwards, stop yourself from accessing that site for the meantime and install the necessary plugins that that site needed. If you can post the exact address of that site so I can visit it and check what is causing it the better.

You can use mozilla firefox (safe mode) or internet explorer (safe mode) for the meantime to access that site and prevent any hangups on your site. Be sure the browser/s you will use is in Safe Mode.

I would suggest you to try the following methods and check if it works for you.

Method 1:
Try the steps provided in the following Microsoft Support article to troubleshoot script errors in Internet Explorer and check if it helps.

How to troubleshoot script errors in Internet Explorer:
http://support.microsoft.com/kb/308260/en-us?wa=wsignin1.0

Method 2:
Try the steps provided in the following Microsoft Help article and check.

Is Internet Explorer slow? 5 things to try:
http://windows.microsoft.com/en-us/windo...ost-performance
Disclaimer: The Reset Internet Explorer Settings feature might reset security settings or privacy settings that you added to the list of Trusted Sites. The Reset Internet Explorer Settings feature might also reset parental control settings. We recommend that you note these sites before you use the Reset Internet Explorer Settings feature.