Remove Avatar Upload from custom Signup Page

Hey there

I made a custom signup page for my multisite installation by copying the signup.php into a custom template. Of course i made a few changes to that.

Anti-Splog, and the Remove E-Mail verification Plugin are working well with my custom signup. I also just removed some minor code.

After activating Avatars, some kind of jQuery error appeared which says "ajaxfileupload" is not a function.

After I replaced my custom form with the standard signup form everything worked well again - but of course this is not what i want

I would like to remove the avatar upload form the signup-form completely, is there a way to do this? Maybe by a filter?

I also receive the message below, after deactivating Avatars network wide:

Warning: Missing argument 2 for update_site_option(), called in /mypath/wp-content/plugins/avatars/avatars.php on line 140 and defined in /mypath/wp-includes/option.php on line 1200

Thank you!