Did something went wrong about GL_ARB_sync extension with recent win7-64 opengl drivers?

I have an OpenGL based program which make heavy use of GL_ARB_sync extension when running it under Windows 7 x64, it used to work well with both NVIDIA and AMD video card. But with recent version of NVIDIA driver The performance of my program regressed significantly. I have three NVIDIA cards, Geforce 860GT, Gefore GT 740 and Gefore 660 Ti,they are both affected, my program always become unresponsive and sometimes the whole desktop system even freeze!
For example, My program works well under 337.88 NVIDIA driver, but become nearly usuable with driver such as 347.25.
It seems that the implementation of GL_ARB_sync extension of recent NVIDIA opengl driver has changed. Did someone also encounter the same problem like me? can somebody help me? thanks!

Could you provide instruction and binary to run your program? I can file a bug against NVIDIA driver team.