Probabbly duplicate of http://devnet.jetbrains.com/message/5116675#5116675
Some times I had issue "Cannot resolve symbol" for my asp.net controls when I declare ID but I wasn't sure if it VS2010 or Resharper issue. But now I collected a bit more information that random error ocurrence that I had before.
Now it 100% Resarper issue because when I suspend resparper this error disappears and when resume Resharper I again got this error. And it appears second time in row when I copy control declaration from aspx page in one project in solution to aspx page in another project in solution.
In my case it was:
<asp:Literal ID="Greeting" runat="server">Unknown User</asp:Literal>
To fix that problem helps only Visual Studio restart and manualy declare new control on aspx page and save this page.
JetBrains ReSharper 7.1 C# Edition
Build 18.104.22.168 on 2012-11-13T19:34:00
Licensed to: Vladimirs Surajevs
#1. “Spell Checker for Resharper” v22.214.171.124 by “Artem Bukhonov”
#2. “You Can't Spell” v1.1.4701.40448 by “Aaron Dandy”
Visual Studio 10.0.40219.1.