I need some help with this...

One of my colleague,
for this entry purpose will be called,
Sandy.

Lemme ask u first,
have u had a colleague who seems sad all day long?
sad, moody, not smiling kinda face?

Yes i have one too!
Sandy...

And i m beginning to get negative vibes from her,
its eating up my energy and enthusiasm..
how???

i asked her just this evening "How are you?"
She said "ok"
.........
The whole evening,
not only on one ocassion that this happened,
comes back to the back of the hse and starts "cursing" about...
uncivilised guests etc...
shouldn't allow children in the club lounge etc...
and best of all,
slams her stuff all over.

And there i am just by the side,
wondering what's going on within her?

LIKE WHAT THE HELL LAR!!!

I come to work smiling,
but all i want is for 10pm to come quickly.

To a certain extent i m enjoying my experience at the club,
meeting new guests,
dealing with challenging guests,
the desire to delight them with many memorable experiences, subtley.

But -
This woman is eating me up.

What should i do?

Or rather what would you do?

*bearing in mind - i'm new to the co., and she is on good terms with the boss