2000 Ford Escort - hard to get out of park

I have a 2000 Ford Escort and just started having this problem. I start the car in the morning after it has sat all night, or after it has sat for several hours and the gear selector will not budge. After trying form about a half hour it will finally go into gear. What could be the cause of this and how can I fix this problem.

I only work on call so I will make a donation as soon as I get my next check from working this last weekend.

Thank you!