the time to make regular backups of your internal disk is when it’s working properly. Even if you can make backups of your files now, the originals might already be corrupted.
What you can try is this: boot your MacBook Pro into Recovery mode by holding down a Command key and the R key as it starts up. Once the OS X Utilities menu appears, select Disk Utility. On the left-hand side of the Disk Utility window, select your internal disk’s boot partition (typically called “Macintosh HD”). On the right-hand side, press the Verify Disk button if it’s not greyed out; if it is greyed out, or if it reports that errors were found, press the Repair Disk button. Once the verification/repair is completed, exit Disk Utility and select Restart from the Apple menu to restart in normal mode. Does your MacBook Pro still freeze up?