If you're using 1.2V nominal AA batteries they are probably NiMH rechargeables. Note that these are likely to be 1.4V or more when fully charged. Pushing 14V+ into the Vin pin is a bad idea.
Running motor drivers from the 5V pin is also bad unless they are VERY small VERY low current motors.
And powering any relatively high current devices via breadboard can also cause all sorts of problem.
Steve