System.TypeInitializationException: The type initializer for 'NpgsqlTypes.NpgsqlTypesHelper' threw an exception. ---> System.TypeLoadException: Could not load type 'System.DateTimeOffset' from assembly 'mscorlib, Version=2.0.0.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089'.
解决办法：需打上Microsoft .NET Framework 2.0 Service Pack 1 (x86)补丁，下载地址：
http://www.microsoft.com/downloads/zh-cn/details.aspx?familyid=79bc3b77-e02c-4ad3-aacf-a7633f706ba5
另外，可能还需要安装Windows Installer 3.1，下载地址：
http://www.microsoft.com/downloads/zh-cn/details.aspx?FamilyID=889482fc-5f56-4a38-b838-de776fd4138c