In a lot of cases inappropriate behaviour is caused by high arousal levels, a lack of training and mental and physical exercise. Chances are really good that solitary confinement is going to make it worse because the dog is bored out of its mind. That approach will not settle the dog down or make her calmer.
Solitary confinement is a training method if you want to coerce a dog into submission and shut her down. Not an appropriate approach in 2015 (and has never been). I call it abuse.
If a dog has a problem it should be trained and that requires (positive) interaction and a lot of mental and physical stimulation. Dog training should be fun for both, owners and dogs.
If I get called after in after this kind of advice, the owner and dog are distressed. Mostly the owner feeling really bad, saying: It just felt wrong. If it feels wrong it probably is wrong.
And this is one of our senior dogs in class all dressed up for graduation!