Thank you for the information and for your patience with this issue but rest assured that if McAfee is the one that’s causing this, the webpage will be blocked instead of simply not allowing us to scroll up and down. Also the hardware change should not affect MSN this way.
It is possible that your account settings in MSN are already corrupted. I will be providing the steps to fix this. Before you follow them, please make sure that you back up all e-mails that are stored in 'Folders in your Computer' on your MSN making sure that we won't lose anything in the process.
Please follow the Method 1 steps on this link to back up the email messages: http://answers.msn.com/solution.aspx?solutionid=d830f08c-414d-49ae-91cb-df58aa44832f If you have several e-mail accounts, sign in on the other email address then follow the steps on the link but change the last part of the file name so that you can identify the backed up email. For example, instead of leaving it as MSN_Mail.msnbak you can change it to MSN_(e-mail address).msnbak.
Once the email messages are backed up, please follow the steps on this link to perform CTRL+SHIFT+F11 which refreshes the account settings: http://answers.msn.com/thread.aspx?threadid=d2de6731-17a3-41fd-9fde-c9185947dfc5
Feel free to reply to this post for any questions and feedback.
Thanks!