Insanity and bad knees.

Hey Guys! I wanted to ask if any of you having problems with their knees tried doing Insanity? I have some undiagnozed issues with my knees, especially left one. Walking down the stairs used to bring some pain, but I'm happy to notice that half way through week 3 of Ripped in 30 this pain is gone (although my left knee makes popping sound when walking UP the stairs this time). I'm wondering if Insanity will be bad for my knees? Any advice?