No comment possible without cookies

Hi there,

running the latest Version (V 1.5.3) someone stated the following error, after adding a comment:

Fatal error: Call to a member function on a non-object in /webroot/gallery/classes/User.php on line 281

after testing and not seeing this problem i thought of something else.

I blocked all cookies..and voila..
this error appeared.

is there a way to allow adding of comments without cookies?

As i just can not thing of a way to use cookies, if there is no user to login..

Means anonymous comments allowed..

Any kind of help would be appreciated..

Marcel