Re: Segmentation fault when accessing members

I'm having this weird problem where I am segfaulting whenever I try to
access a member of my class:

class LookupTable {
    typedef boost::upgrade_lock<boost::shared_mutex> ReadLock;
    typedef boost::upgrade_to_unique_lock<boost::shared_mutex> WriteLock;
public:
    unsigned long query(unsigned int k, const Evaluator& eval) {
        // accessing results or mutex in any way segfaults here
    }
private:
    std::map<unsigned int, unsigned long> results;
    boost::shared_mutex mutex;
};

Another similar class (a class that manages LookupTable instances) has
a similar structure (in terms of its similarities with query()), but
doesn't segfault. Any thoughts as to be why this could happen?