When there are any parenthesis in the customer's last name, the customer lookup is broken. For instance, I log in to admin and from the homepage I see a list of "New Customers". If I click to user's name there to search for them, I get the following error:

1139 Got error 'parentheses not balanced' from regexp
in:
[select count(*) as total from customers c left join customers_info ci on c.customers_id= ci.customers_info_id left join address_book a on c.customers_id = a.customers_id and c.customers_default_address_id = a.address_book_id where c.customers_lastname like '%List - ( Carniva Miracle%' or c.customers_firstname like '%List - ( Carniva Miracle%' or c.customers_email_address like '%List - ( Carniva Miracle%' or c.customers_telephone rlike 'List - ( Carniva Miracle' or a.entry_company rlike 'List - ( Carniva Miracle' or a.entry_street_address rlike 'List - ( Carniva Miracle' or a.entry_city rlike 'List - ( Carniva Miracle' or a.entry_postcode rlike 'List - ( Carniva Miracle']
If you were entering information, press the BACK button in your browser and re-check the information you had entered to be sure you left no blank fields.