2001 Toyota Corolla front end screeching

I took my car to have the brakes checked because when I stop at times (not always), there is screeching coming from under the front of the car. The brakes were checked twice and I was told they were okay. They drove the car but said they did not get the screeching sound. I know I'll probably have to take the car to the dealer but I wanted some idea up front of probable causes of the screech.
Note: It's not scrubbing but sqealing. Please help!