Even if I use:

 

<script language=javascript>
window.open('<%=CuteSoft.Chat.ChatWebUtility.ResolveResource(Context,"IM_MainForm.Aspx")%>','','status=1,width=340,height=500,resizable=1')
</script>

 

Its the same error. If I call the messenger from the normal default.aspx, I am able to open it.

 

thanks.