Registration internal error

My customers are getting an internal error when registering. Is there anyway I can fix it? Make it simple, I am not an expert at this. Thanks!
Here is the log:
[The type of log entry.] Log type:      Unknown
[The severity of the log entry.] Severity:   11
[The log entry message.] Message:   Exception of type 'System.Web.HttpUnhandledException' was thrown.
[The exception details for the log entry.] Exception:   System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object. at NopSolutions.NopCommerce.Web.Modules.CustomerRegisterControl.CreatedUser(Object sender, EventArgs e) in D:\Work\Own\NopCommerce\Solution\PublishedSite\Solution\NopCommerceStore\Modules\CustomerRegister.ascx.cs:line 177 at System.EventHandler.Invoke(Object sender, EventArgs e) at System.Web.UI.WebControls.CreateUserWizard.OnCreatedUser(EventArgs e) at System.Web.UI.WebControls.CreateUserWizard.AttemptCreateUser() at System.Web.UI.WebControls.CreateUserWizard.OnNextButtonClick(WizardNavigationEventArgs e) at System.Web.UI.WebControls.Wizard.OnBubbleEvent(Object source, EventArgs e) at System.Web.UI.WebControls.CreateUserWizard.OnBubbleEvent(Object source, EventArgs e) at System.Web.UI.WebControls.Wizard.WizardChildTable.OnBubbleEvent(Object source, EventArgs args) at System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) at System.Web.UI.WebControls.Button.OnCommand(CommandEventArgs e) at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace --- at System.Web.UI.Page.HandleError(Exception e) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest() at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) at System.Web.UI.Page.ProcessRequest(HttpContext context) at ASP.register_aspx.ProcessRequest(HttpContext context) in c:\windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\cheesesupplies\656c527d\62d762ef\App_Web_oydxsajg.0.cs:line 0 at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
[IP address of the machine that caused the exception.] IP address:   74.95.141.225
[Name of the customer who caused the exception.] Customer:   
[Originating page of exception] Page URL:   http://winddancevineyard.com/cheesesupplies/Register.aspx
[Date/Time the log entry was created.] Created on:   1/20/2010 9:17:28 AM

Ok, I tracked down the computer guy at my office and he helped fix this. The problem was caused when I removed the requirement for date of birth and gender in the registration form (modules/customerregistration.ascx) using notepad. I simply deleted them not knowing that another file would need response to this data.

So, I downloaded the same version of nopcommerce that I have (1.30), and copied the lines of text I removed from the new copy of customerregistration.ascx to my old copy (the copy on my server). Then I changed the text to the following (see below - added visible= "false" in 4 places, and deleted one line of the gender code and dob code). And all is well, with gender and date of birth removed from the registration page and no more error code.

<div class="SectionBody">
                            <table class="TableContainer">
                                <tbody>
                                    <tr class="Row">
                                        <td class="ItemName">
                                            
                                        </td>
                                        <td class="ItemValue">
                                            <asp:RadioButton runat="server" ID="rbGenderM" GroupName="Gender" Visible="false" Text="Male" Checked="true" />
                                            <asp:RadioButton runat="server" ID="rbGenderF" GroupName="Gender" Visible="false" Text="Female" />
                                        </td>
                                    </tr>
                                    <tr class="Row">
                                        <td class="ItemName">
                                            <%=GetLocaleResourceString("Account.FirstName")%>:
                                        </td>
                                        <td class="ItemValue">
                                            <asp:TextBox ID="txtFirstName" runat="server" MaxLength="40"></asp:TextBox>
                                            <asp:RequiredFieldValidator ID="rfvFirstName" runat="server" ControlToValidate="txtFirstName"
                                                ErrorMessage="First name is required." ToolTip="First name is required." ValidationGroup="CreateUserForm">*</asp:RequiredFieldValidator>
                                        </td>
                                    </tr>
                                    <tr class="Row">
                                        <td class="ItemName">
                                            <%=GetLocaleResourceString("Account.LastName")%>:
                                        </td>
                                        <td class="ItemValue">
                                            <asp:TextBox ID="txtLastName" runat="server" MaxLength="40"></asp:TextBox>
                                            <asp:RequiredFieldValidator ID="rfvLastName" runat="server" ControlToValidate="txtLastName"
                                                ErrorMessage="Last name is required." ToolTip="Last name is required." ValidationGroup="CreateUserForm">*</asp:RequiredFieldValidator>
                                        </td>
                                    </tr>
                                    <tr class="Row">
                                        <td class="ItemName">
                                            
                                        </td>
                                        <td class="ItemValue">
                                            <asp:TextBox runat="server" ID="txtDateOfBirth" Visible="false"/>
                                            <asp:ImageButton runat="Server" ID="iDateOfBirth" Visible="false" ImageUrl="~/images/Calendar_scheduleHS.png"
                                                AlternateText="Click to show calendar" /><br />
                                            <ajaxToolkit:CalendarExtender ID="cDateOfBirthButtonExtender" runat="server" TargetControlID="txtDateOfBirth"
                                                PopupButtonID="iDateOfBirth" />
                                        </td>
                                    </tr>