Application error on Page, what i am doing wrong?
<p>I have a basic web forum people fill out and send an e-mail. I have about two dozen of them on the site. One is not working in IE for some reason. It works and sends fine in Firefox, Chrome, Opera etc...</p>

<pre><code>IE error:

Server Error in '/' Application.
--------------------------------------------------------------------------------

Invalid postback or callback argument. Event validation is enabled using in     
configuration or &lt;%@ Page EnableEventValidation="true" %&gt; in a page. For security   
purposes, this feature verifies that arguments to postback or callback events 
originate from the server control that originally rendered them. If the data is valid 
and expected, use the ClientScriptManager.RegisterForEventValidation method in order 
to register the postback or callback data for validation.

Description: An unhandled exception occurred during the execution of the current web   
request. Please review the stack trace for more information about the error and where 
it originated in the code.


Exception Details: System.ArgumentException: Invalid postback or callback argument.  
Event validation is enabled using in configuration or &lt;%@ Page  
EnableEventValidation="true" %&gt; in a page. For security purposes, this feature 
verifies that arguments to postback or callback events originate from the server 
control that originally rendered them. If the data is valid and expected, use the 
ClientScriptManager.RegisterForEventValidation method in order to register the 
postback or callback data for validation.
</code></pre>

<p>Source Error:</p>

<pre><code>An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
</code></pre>

<p>Stack Trace:</p>

<pre><code>[ArgumentException: Invalid postback or callback argument. Event validation is    enabled     
</code></pre>

<p>using in configuration or &lt;%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the
    ClientScriptManager.RegisterForEventValidation method in order to register the<br>
    postback or callback data for validation.]
    System.Web.UI.ClientScriptManager.ValidateEvent(String uniqueId, String argument) +159
    System.Web.UI.Control.ValidateEvent(String uniqueID, String eventArgument) +108
    System.Web.UI.WebControls.DropDownList.LoadPostData(String postDataKey,<br>
    NameValueCollection postCollection) +55
    System.Web.UI.WebControls.DropDownList.System.Web.UI.IPostBackDataHandler.LoadPostData(Stri    ng postDataKey, NameValueCollection postCollection) +11
    System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad) +353</p>

<pre><code>System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean      
includeStagesAfterAsyncPoint) +1194
</code></pre>
