So in order to fix some of the issues described above like the expression error and the OP error you need to do a few common things. First, after downloading the zip file, right click and hit "UNLOCK" on the properties menu. THis way when you unzip the sample all of the included binaries will now be unlocked and useable. You should no longer have any errors at this point except the one that I have below.
Error 6 RIA code generation failed to construct OpenAccess context: No metadata has been registered for class 'CRM.DataAccess.Activity, CRM.DataAccess, Version=126.96.36.199, Culture=neutral, PublicKeyToken=null'. (This usually indicates, that either this class is not declared persistent or it is declared persistent but not enhanced. The class was loaded from file:///C:/Projects/CRM/CRM_Dev_2012_3_1017/CRM.Web/bin/CRM.DataAccess.DLL
You will get this error on CRM.Repository, Companies, Dashboard, Activities, Contacts and Opportunities when you do a rebuild or build on the solution. The only projects that build individual are the ones not listed above. Can you advise a work around for this?
I have tried cleana nd rebuild but it fails. I have also tried bebuilding individual projects and they build fine except for the projects mentioned above. Not sure whats causing this error as I have yet to figure out a resolve by normal measures.