My almost 2 year old dog has started having accidents in the house. She doesn't have any accidents when I'm gone or at night but when I get home from work and on the weekends it seems like about once every hour or two she'll walk up to where ever I am and squat and have an accident.

I would get her checked out for a urinary tract infection.
It is rare for dogs behaviour to just suddenly change with no reason.
Has anything different happened around the house that could cause her behaviour to change? (New pets, people leaving or coming etc)