S-R latch

Hi ,

the following is the implementation of S-R latch which i saw  in a
book,

http://i297.photobucket.com/albums/mm220/sophiaagnes/Scan3.jpg

and the following is the truth table based on it
http://i297.photobucket.com/albums/mm220/sophiaagnes/scan2.jpg


 now in  the book it is written that when both s & R are made high
simultaneously both the o/p will be low
 and the value of Q is unpredictable (1 or 0)  depending on the
circuit condition

 now my question is what is this circuit condition that Q depends on ?