ASP 2.0 breaks Validation giving WebForm_PostBackOptions is Undefined

[RobHydell]

After I upgraded to .NET 2.0 I started getting the following Error:
'Webform_PostBackOptions' is undefined when calling
javascript:WebForm_DoPostBackWithOptions(new
WebForm_PostBackOptions("dlstDataList$ctl01$LinkBu ttonT3", "", true,
"", "", false, true))

After I remove the following RequiredFieldValidator control it works
perfectly. It also works perfectly if I leave the
RequiredFieldValidator in but switch back to .NET 1.1. This also
happens with any of the other ASP.NET validators, Any ideas? Missing
some required javascript file?

<asp:TextBox id="Project" Columns="100" CssClass="FormControls"
Runat="Server" Text='<%# DataBinder.Eval(Container.DataItem,
"Project")%>'/>

<asp:RequiredFieldValidator id="RequiredFieldValidator1"
ControlToValidate="Project" runat="server" ErrorMessage="Error !"/>

[RobHydell]

Has anyone seen this error before?
Thanks in advance... Ro*******@Hotmail.com