ASP.Net double-click problem

having a slight problem with an ASP.net page of mine. If a user were to double click on a "submit" button it will write to the database twice (i.e. carry out the 'onclick' method on the imagebutton twice)

How can I make it so that if a user clicks on the imagebutton, just the imagebutton is disabled?

I've tried:

<asp:ImageButton 
     runat="server" 
     ID="VerifyStepContinue" 
     ImageUrl=image src 
     ToolTip="Go" 
     TabIndex="98" 
     CausesValidation="true" 
     OnClick="methodName" 
     OnClientClick="this.disabled = true;" />

But this OnClientClick property completely stops the page from being submitted! Any help?

Sorry, yes, I do have Validation controls... hence the icky problem.

Working on this still, up to this point now:

ASP code:

 <asp:TextBox ID="hidToken" runat="server" Visible="False" Enabled="False"></asp:TextBox>
 ...
 <asp:ImageButton runat="server" ID="InputStepContinue" Name="InputStepContinue" ImageUrl="imagesrc" ToolTip="Go" TabIndex="98" CausesValidation="true" OnClick="SubmitMethod" OnClientClick="document.getElementById('InputStepContinue').style.visibility='hidden';" />

C# code:

         private Random
    random = new Random();


    protected void Page_Load(object sender, EventArgs e)
    {
        //Use a Token to make sure it has only been clicked once.
        if (Page.IsPostBack)
        {
            if (double.Parse(hidToken.Text) == ((double)Session["NextToken"]))
            {
                InputMethod();
            }
            else
            {
                // double click
            }
        }

        double next = random.Next();

        hidToken.Text = next + "";
        Session["NextToken"] = next;

Actually... this nearly works. The double click problem is pretty much fixed (yay!) The image still isn't hidden though.