NVIDIA has released the Optimus 189.42 drivers for notebooks with this new switchable graphics technology. The update fixes an incompatibility problem with Intel's latest integrated graphics drivers. Moreover, it also features some performance and functionality improvements.
* Fixes incompatibility issue with Intel IGP (March) driver
* Performance and functionality improvements
* Corrects merging issue with Optimus Profile updates
You can download it over here (32-bit) or here (64-bit).