It seems a bug of the DotNet2.0Beta .
I have try many times for this issue . many code have the same problem :(
So I would not change the code for this issue .
The origin CuteEditor.dll is OK . Just the protected CuteChat.dll (using Dotfuscator) have this problem .
I have send a bug report to microsoft .
If the problem still not be resolved when the DotNet2.0 Release Version is out , and the new release of Dotfuscator is out .
I think we would not use the Dotfuscator too .