Q: BOOTCAMP PROBLEM IN OSX YOSEMITE

1. In Disk Utility, run Disk Repair and try BCA.

2. Boot in Safe Mode - Startup key combinations for Mac - Apple Support and Try safe mode if your Mac doesn't finish starting up - Apple Support and then boot normally and try BCA.

3. Try the following two steps and then try BCA.

     Resetting the System Management Controller (SMC) on your Mac - Apple Support

     How to Reset NVRAM on your Mac - Apple Support

If you still run into issues, you may have to back up, erase internal disk and restore and then try BCA.

1. Back up OSX using Time Machine - Mac Basics: Time Machine backs up your Mac - Apple Support.

2. Boot into Internet Recovery - OS X: About OS X Recovery - Apple Support.

3. Erase your internal drive and restore from the TM backup in Step 1 - OS X Yosemite: Recover your entire system.

Please be aware that TM does not backup Bootcamp partitions.