Anyone ever played Warrior Within?Follow

I got this game last year for Christmas and got a very badly glitched copy. I returned it to the store for another disc, which was also a very badly glitched copy (music sometimes buzzes loudly, loading screens freeze, enemies go invisible and I'm talking like crows go invisible, Dahaka randomly appears in some places and just stands there, in places where the Dahaka is supposed to appear he doesn't, etc, etc.). The reason I am just now talking about this is I heard there was a secret ending if you get all of the life upgrades, and I was playing through it again to accomplish this. However, my game loaded an area incorrectly (about 3/4 through the game, a lever is supposed to be up which isn't) and it loaded the prince as the Sand Wraith when he wasn't supposed to be. I can't figure out anyway to get past this glitch, and I'm so close to getting to the secret ending I've wanted. So, my question is:

1.) Are all the copies of Warrior Within glitch-crazy?

2.) How can I beat the bad glitch I have?

I was thinking about going and trying to rent the game and see if another copy would fix it...

very glitchy but its pretty cool at what u can do with the character. Its alright but after i got so far i got stuck and never played agin lol.

I got the secret ending and was amazed. Too bad the secret ending boss is easy as hell... he was about as stupid as the boss from persia 1 -_-

In my opinion, any final boss that you can beat on the first try is too easy lol.