MacOS X 10.6.8 - 2.8 GHz Quad-Core Intel Xeon - 6GB 1066Mz DDR3 - ATI Radeon HD 5870 1024Mb VRAM
Windows 8.1 64 bits - i5-3320M - 8GB DDR3 - NVIDIA GeForce GT 635M 2048Mb
Blender 2.70a
The same error occurred in these two systems. When you select an edge and apply bevel, with 2 or more segments and you can't go bellow 0,001 meter in the amount and mantain the profile at 0.5... The bevel is still visible but under 0,001 meter, but it goes flat.
Set units to meter, i didn't try otherwise, create some mesh object, active edit mode, select one or more edges, apply bevel, set segments to 2 or more with the mouse wheel, set the profile to 0.5 and the amount to less than 0.001.
I hope can figure out what's the problem and solve it because this feature is very important to reproduce real world precise machinary.
Thanks for the excelent 3D package and keep pushing! Best regards!