The recount of the tournament at Harrenhaal tells us that one of the Starks fell for Ashara Dayne and got her pregnant. It is widely believed that this was Eddard - but the only reason for this seems to be the Eddard/Ashara connection and the rumours of her being John Snow's mother. Such a thing would have been extremely out-of-character for Eddard and Brandon also seems unlikely as, at that point, he was both betrothed to Catelyn and in a tryst with the future Lady Dustin (though this does not rule him out altogether).

However, if we consider the only other character who knew the situation well - Barristan Selmy, who was in love with Ashara - he dismisses the notion of Ashara being John Snow's mother; saying her child was a stillborn girl - the grief over which drove Ashara to suicide. He also (as Meera did) avoids naming the father - referring to him simply as "Stark".

If it was not Eddard but Benjen who impregnated Ashara at Harrenhaal, this would provide a far greater reason for him to take the black - his daughter died at birth and the woman he loved killed herself with the grief of it.

Furthermore, if other theories (already noted in previous comments above) about John Snow's parentage are correct - and if Eddard knew of Benjen and Ashara's child - then this theory also explains why Eddard went to Starfall under the pretence of returning Arthur Dayne's sword (surely, given the circumstances, that could have waited a few weeks?) - he knew a Stark bastard was due to be born there and perhaps hoped to pass the infant Jon off as a twin or even replace Ashara's child with Jon.

Why did Benjen Stark take the Black?
I'm using Windows XP and I hate the long start up time when I shut down and then turn on my laptop. However if I hibernate instead of shutting down it starts up much faster. Are there any harmful effects / disadvantages if I always hibernate whenever I'm done for the day instead of shutting down?
