This may sound like a basic question but... I really cant figure it out. Any suggestions will help before I take it to a dealership.

Not sure if it matters cause its a braking question but... its a Honda CR-V.

Its a friends and she wanted me to take a look at it to see if I can fix it. Been driving it for 3 days and just now had it happen to me. The car shakes and vibrates when you press on the brakes. More on hill declines. But, here is the funny part...within three days... I have driven the same stretch of highway and city road. Same route, same routine... like 7 times. This braking problem has happened only once out of the 7 trips. I would assume if there was a problem it would happen all the time. Anyways... that was a short story long.