It it only the MSN is not responding or are there any other applications that are not responding simultaneously?
Mean while what would be the CPU usage go up to?
Can you upload any screanshot of the background processes in taskmanager during the same.
Untill then try deleting all the temporary files and cookies from your C:/ drive and fix registry file errors using "Ccleaner" application. And also reset the browser and check if there is any progress.
Thank you :)