There is a URL Filtering rule applied to a group that blocks access to a category of URLs. However, an end user who is not a member of this group also complains that he is being blocked from accessing sites within that category.
After verifying that no other policies might be preventing the user from accessing these sites, check the LDAP directory service to see what groups the end user belongs to. It is very likely that his group membership changed since the last time PCIP synced up with LDAP. Once PCIP syncs, the end user will no longer be associated with his former group and will be able to access those sites.