403 errors on Options saving.

I’ve got a plugin with its own options page which uses the new method. So the form starts:

echo'<p><hr><h3>';
		_e('Blog Level Customisation');
		echo'</h3><form action="options.php" method="post" action="">';
		settings_fields('wordbooker_options');

and finishes:

if (current_user_can('activate_plugins')) {echo '<input type="submit" name="SBLO" value="'.__("Save Blog Level Options").'" class="button-primary"  />&nbsp;&nbsp;&nbsp;<input type="submit" name="RSD" value="'.__("Reset to system Defaults").'" class="button-primary" action="poo" />';}
		echo '</p></form><br /></div><hr>';

This is all working fine apart from one user who when he clicks on the buttons gets a 403 error and it tries to load [blog url]/wp-admin/options.php

when it should of course go to [blog url]/wp-admin/options-general.php?page=myplugin&updated=true

All I can think is that its something in his set up which is:

WordPress: 2.9.1
PHP: 5.2.10
MySQL: 5.0.67
Server : Apache/1.3.41

Anyone got any suggestions? Apart from suggesting he upgrades to 2.9.2