Drupal 4.7.6 and CiviCRM 1.7 User synchronization bug

When synchronizing CiviCRM with Drupal user base, I receive the following error:

Array
(
[callback] => Array
(
[0] => CRM_Core_Error
[1] => handle
)

[code] => -2
[message] => DB Error: syntax error
[mode] => 16
[debug_info] =>
SELECT civicrm_contact.id as contact_id,
civicrm_contact.domain_id as domain_id,
civicrm_contact.hash as hash,
civicrm_contact.contact_type as contact_type,
civicrm_contact.contact_sub_type as contact_sub_type
FROM civicrm_contact
LEFT JOIN civicrm_location ON ( civicrm_location.entity_table = 'civicrm_contact' AND
civicrm_contact.id = civicrm_location.entity_id AND
civicrm_location.is_primary = 1 )
LEFT JOIN civicrm_email ON ( civicrm_location.id = civicrm_email.location_id AND civicrm_email.is_primary = 1 )
WHERE civicrm_email.email = 'nancy.o'regan@nscc.ca' AND civicrm_contact.domain_id = 1 [nativecode=1064 ** You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'regan@nscc.ca' AND civicrm_contact.domain_id = 1' at line 11]
[type] => db_error
[user_info] =>
SELECT civicrm_contact.id as contact_id,
civicrm_contact.domain_id as domain_id,
civicrm_contact.hash as hash,
civicrm_contact.contact_type as contact_type,
civicrm_contact.contact_sub_type as contact_sub_type
FROM civicrm_contact
LEFT JOIN civicrm_location ON ( civicrm_location.entity_table = 'civicrm_contact' AND
civicrm_contact.id = civicrm_location.entity_id AND
civicrm_location.is_primary = 1 )
LEFT JOIN civicrm_email ON ( civicrm_location.id = civicrm_email.location_id AND civicrm_email.is_primary = 1 )
WHERE civicrm_email.email = 'nancy.o'regan@nscc.ca' AND civicrm_contact.domain_id = 1 [nativecode=1064 ** You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'regan@nscc.ca' AND civicrm_contact.domain_id = 1' at line 11]
[to_string] => [db_error: message="DB Error: syntax error" code=-2 mode=callback callback=CRM_Core_Error::handle prefix="" info="
SELECT civicrm_contact.id as contact_id,
civicrm_contact.domain_id as domain_id,
civicrm_contact.hash as hash,
civicrm_contact.contact_type as contact_type,
civicrm_contact.contact_sub_type as contact_sub_type
FROM civicrm_contact
LEFT JOIN civicrm_location ON ( civicrm_location.entity_table = 'civicrm_contact' AND
civicrm_contact.id = civicrm_location.entity_id AND
civicrm_location.is_primary = 1 )
LEFT JOIN civicrm_email ON ( civicrm_location.id = civicrm_email.location_id AND civicrm_email.is_primary = 1 )
WHERE civicrm_email.email = 'nancy.o'regan@nscc.ca' AND civicrm_contact.domain_id = 1 [nativecode=1064 ** You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'regan@nscc.ca' AND civicrm_contact.domain_id = 1' at line 11]"]
)