Webplayer exception when using BufferedStream

Hi all,

previously, I asked a more or less similar question, but boiled it down a bit.

I created a new, empty project, added a script to an object which, on start, just executes:

MemoryStream test = new MemoryStream();
BufferedStream bStream = new BufferedStream(test);

Which works fine in the Editor (WebPlayer mode) but throws an exception when starter in the browser:

MethodAccessException: Attempt to access a private/protected method failed.
at System.Security.SecurityManager.ThrowException (System.Exception ex) [0x00000] in <filename unknown>:0 
at testScript.Start () [0x00000] in <filename unknown>:0

You can also just download the complete project folder here: http://rapidshare.com/files/453806948/testUnityProject.zip

Both classes MemoryStream and BufferedStream should be fully supported by the web player, according to the documentation.

Any help is appreciated :) Thanks for all hints.