Getting crushed on stars lately..what point do you call it quits?

[ClubChamp04]

I lost about 3.5 buy ins today at 100nl and it just drives me crazy with the beats I'm taking. I have a hard time quiting and continue playing trying to get back to some reasonable loss # on the day with no success. I definitely couldn't of won today no matter how good I played, it was just one of those "doomswitch" days.

So...any tips on when to hang it up for the day? Maybe I should just quit when the beats start coming and I feel a doomswitch day coming on...