<asp:linkbutton id="lnkMenu" runat="server" fontnames="<%#Eval("FontName")%>" font-size="<%#Convert.ToInt32(Eval("FontSize"))%>" text="<%#Eval("Name")%>" commandargument="<%#Eval("ID") %>" tooltip="Select" onclick="Repeater_Click" xmlns:asp="#unknown"> </asp:linkbutton>
the problem is in ur code,u are assigning collection to strings ie.font1,font2,..etc to Font Names property,so it gives error like
"Unable to cast object of type 'System.String' to type 'System.String[]'"
refer
<asp:linkbutton id="runView1PerPage" font-names="Verdana, Arial" runat="server" xmlns:asp="#unknown"></asp:linkbutton>