Let's think about this one...
You are in intense muscle pain...
One commenter said that they could not lower herself into a chair without pain...
Does muscle soreness equate to something being a good program?
Sorry, but P-90x is the not the best approach to training. Will it wear you out? Yes. Will it help you lose weight along with proper nutritional strategies? Yes - but, so will any sort of hardcore intense activity ranging from being chased by bulls to performing intense manual physical labor.
The problem with P-90x is that it doesn't follow a true progression, it doesn't address any movement inefficiencies that you may have, and it prescribes far too much volume - i.e. it gives you WAY more than you truly need to be fit and healthy.
Plus, it has people doing "plyometrics." Jumping up and down is not the purpose of plyometrics. I imagine that Yuri Verkhoshansky, the father of plyometrics and a Russian sport scientist and researcher, is probably rolling over in his grave right now at the blatant misuse and misinformation about plyometric training. Not to mention, is it real safe for an out-of-shape 250 lb guy to be doing plyometric training? Probably not!
Not to mention, who's around to monitor the knee position upon landing? If the knee is caving in, that's probably not good - especially for the females since females do have an increased ACL risk of about 6 or 7 to 1 in comparison to males.
Here's my suggestion - send it back and get your money back. I could direct you to a lot better resources for your $100 or $150 bucks or whatever you spent.
Here's a great blog post from a guy who's a strength coach/trainer and is in PT school that really sums it up well:
The reality is this - you don't have to beat the hell out of yourself to get into shape. Train smart - not hard!