OS X 10.8.5
NVIDIA GeForce GT 650M 1024 MB
Broken: 2.71 2f03ccc and offical 2.71 9337574
When animating the bevel factor of a complicated bezier curve, Blender crashes when using "spline" or "segments" for the beginning and end bevel factor. When using "resolution" there is no problem. If the end bevel factor is 1, it's okay, but as soon as you make it smaller, Blender crashes. On simple curves it's no problem, but on complicated/heavy curves it is.
If it helps, the error message from the console:
blender(1001,0x7fff75fe0180) malloc: *** error for object 0x108585608: incorrect checksum for freed object - object was probably modified after being freed. *** set a breakpoint in malloc_error_break to debug)
Exact steps for others to reproduce the error
Open attached blend-file and change the end bevel factor.