My EventViewer shows this event repeatedly....any suggestions?

Thanks for your response.

I am noticing that this event only is displayed in the event viewer if I log in as a superuser, but not if I log in as an admin, so I guess I don't need to stress over it.

But I was concerned because immediately after the application is started again, the next event is always an error as shown below, but this error only is displayed to superusers:

Should I worry about this?

Thanks again for your replies.

I remembered that I had made a chage to the skin file Horizontal Menu - Fixed Width.ascx. I had wanted to get rid of the search box in the menubar. I had commented out the html on line 33 <%--<dnn:SEARCH runat="server" id="dnnSEARCH" showWeb="True" showSite="True" />--%> In light of your last reply, I put the control back in, retsarted the application, checked the event viewer, and voila, no more mysterious error. 

However, I would still like to hide the search box. Could you suggest a way I could do so as not to cause an error?

Never mind, I hid the search box again, restarted the application, checked the event viewer, and now there is no error. I'll keep an eye on it and see if I can replicate.