ah..the dumb 'what's your biggest weakness' question.I remember it fondly.
If it's a phone interviewer who says that question, think of him/her like a first tier tech support and use the standard answers like, 'I tend to work too hard sometimes' or 'I tend to be too much of a perfectionist' or whatever.
If it's a personal interview, ie, somebody higher up in the company with more experience...have all the pat answers ready but say them with a look on your face that conveys the message... 'here's the pat answer I got out of a book'.
If he's like most dumb interviewers he'll smile like he's impressed and go on to the next question.
Or he'll smile like he knows that you know it's a dumb question and move on anyways.
Or, if he's got any brains in his head he'll say something like 'ok, that's the standard answer, now what's your real answer'.
Then you just list off a whole bunch of the best standard answers really fast without stopping, (use Google, there's tons of them).
That'll usually be enough to move him onto the next question.

My advice is go out and buy a book on how interviews are conducted.
All the interviewer really wants to know is that you can dress the part, have experience, are personable and can get along with others and take direction ("a team player"), have some intelligence and have done your homework. (ie, read a book on how to be interviewed and already know all the standard answers) know something about the company and their products, (the more you know, the less they have to train you) etc etc...
... and it always helps to be a really cute minority woman with a disability.