c#读取文本文件时的安全异常

我正在编写一个c#程序(具体来说是一个IRC bot)，并使用脚本库Jint (http://jint.codeplex.com/)。我有一个外部命令链接到它，当调用读取。js文本流从不同的文件。读取第一个文件工作正常，但当我读取另一个文件时，我得到的消息是:

System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089' failed.
   at HgpBot.Program.TextFile(String path) in C:'Users'Jake'Documents'Visual Studio 2010'Projects'HgpBot'HgpBot'Program.cs:line 167
   at HgpBot.ExternalCommands.DoFile(Plugin p, IrcEventArgs e, String FilePath)
in C:'Users'Jake'Documents'Visual Studio 2010'Projects'HgpBot'HgpBot'ExternalCommands.cs:line 76
The action that failed was:
Demand
The type of the first permission that failed was:
System.Security.Permissions.FileIOPermission
Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.

public static List<String> TextFile(String path)
        {
            List<String> result = new List<string>();
            try
            {
                using (TextReader tr = new StreamReader(path))
                {
                    String line;
                    while ((line = tr.ReadLine()) != null)
                    {
                        result.Add(line);
                    }
                }    
                return result;
            }
            catch (Exception e) { throw e; }
        }