Deactivating plugins

I was working on several blogs at once and forgot to deactivate the plugins on one site. Now I get the following error:

Warning: array_filter(): The second argument, ‘Array’, should be a valid callback in /hsphere/local/home/alhambra/alhambraproductions.com/blog/wp-includes/capabilities.php on line 152

Warning: Invalid argument supplied for foreach() in /hsphere/local/home/alhambra/alhambraproductions.com/blog/wp-includes/capabilities.php on line 156

And now I cannot access the plugins page to deactivate them.

Any suggestions?

Thanks.