SO's & Friends/Family

Anyone ever had problems with their signifigant others and their friends or family not getting along?  Basically, everyone likes my new girlfriend, except my sister, who inexplicably hates her with a passion.  I've asked my sister why, and she jsut answers to the effect of "I jsut don't like her, that's all."  My girlfriend really doesn't have anything against my sister, so I don't see why there's so much animosity the other way.  They're both pretty important people to me, and I'd like them to at least get along.  Any ideas?

we dont have problems if we are not posting suicide notes... but if you want to talk to a guy with problems... look for the guy who is in love with his sister.