Scripts and Security Issues
While there are other issues that might cause this problem, the first thing you should do is consider the email message itself. Who was it from? What was the message about? Additionally, give some thought to the scrolling action – can it be stopped? Is the message window seemingly scrolling into infinity?
Worse still, is someone else controlling your computer and reading your emails remotely?
One particular cause of this fault could be a script in the email message. While current versions of Outlook should be protected against this type of vulnerability, if you have an older release of the popular email client that hasn’t been patched then there is every chance that the email message features some code that is causing this error.
To prevent this from becoming a larger issue on your system, close Outlook and run your anti-virus software to scan your PC. Additionally, check that Outlook is fully up to date and that you have no updates or hotfixes pending, and arrange for email scanning software to be installed.
Another cause of unusual behavior in Outlook can be the presence of Outlook add-ins, which is software that is installed separately on your computer but is integrated with Outlook. You can check if you are using any add-ins via File > Options > Add-Ins in Outlook 2010, where you will find a comprehensive list of items. If any seem like obvious problems, select Manage > COM Add-ins and click Go… to access a new screen where you can disable any installed add-ins.
Alternatively, if you are reluctant to do this, exit Outlook and then press WINDOWS+R and enter outlook.exe /safe to launch the application in safe mode, without any of the add-ins running. You should find that if the issue occurs now, it is hardware related rather than software/malware.