I have moved your post to the General folder.
I have never heard of this problem related to OneCare. Typically, when a program is flashing in the Task bar, it means that it requires attention as it is in the background and another program is working in the foreground. That doesn't seem to be what you are describing, though. I recommend that you contact support to determine what may be causing the problem - perhaps a conflict between OneCare and other software on the PC, not actually Office applications, but something that is causing the behavior you are encountering.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve