It is possible that there might be something conflicting with OneCare, causing it to access files or scan continually. This could be caused by other security software. It may also be a driver on the PC that causes OneCare to be active. I recommend that you contact support.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
OneCare should have no impact on Outlook Express. What do you mean by funky?
-steve