I have the same problem. Found this thread while looking for a solution for myself.
This thread: http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=970546&SiteID=17
offers several possible explanations/solutions. The most common seems to be the existance of a file "eventvwr.exe.config" in the C:\Windows\System32 directory and deleting or renaming it seems to be the cure.
Other associated possible causes include Peachtree accounting software, MS Office 2007 and Nero 7. (I did not have the .config file, nor Peachtree, but I do have both MS 2007 and Nero 7).
Hope this is of some use to you. Please report here if you found a solution & describe what it was; it might help me (and others).