Debbie,
I think this is extremely common. It's just a phase where they don't want to be contained - wait til she hates her car seat - that's fun. It's up to you if you feel for safety or mess containment that it's important to keep using the high chair.
For me, this was a first "disciplining" step...to help alleviate the power struggles later. I used this "opportunity" to teach my kids that they only got fed in their chairs. My kids are now 5 1/2 and 4 and that's STILL a rule in our house - SITTING in your chair at the table. No walking around with food. No "baby bird" situation where you struggle to get a mouthful of food in your child every time they walk by.
If your child will sit still, try a booster (BIG GIRL CHAIR). If she doesn't behave, go back to the high chair.
It's an easy concept IF YOU STICK WITH IT. Only eat at the table/in her chair. Once she wants to leave, take the food away. Then next time she comes around for food, explain she has to sit down. (Try to avoid the up/down up/down thing. After she gets up from lunch, say all done, no more.) If she hardly eats, next snack offer her some fruit or veggies.
I know "discipline" for a 17 mo old for some sounds silly. However for me, I worked hard from an early age to teach my kids that "I am the rule-maker." We have to sit at the table, no toys, until they are done eating.
So when the rest of your friends are complaining that their kids won't eat, won't sit still, are dragging food crumbs into every room of their house, etc. just smile and say, "Really? That's too bad."
Maybe this is a long answer to your "simple" question, however I sincerely believe it's also the start of the great kid-Mom power struggle of who makes the rules? If she doesn't want to sit, then she doesn't get to eat (yet).
Good luck.