The GeForce drivers 378.49 may have come out of the oven a little undercooked. Users on the GeForce forums are complaining about a myriad of issues, like broken PhysX on Maxwell cards, crashing Java OpenGL apps, and overclocked Pascal cards stuck at reference speeds thanks to drivers' "debug mode" being stuck on. While there's no fix for the first issue yet, Nvidia has addressed the latter two problems with the latest hotfix driver, numbered 378.57.
According to EVGA technical support agent "MDecker," the debug mode is only available on graphics cards with factory overclocks. Digging a bit deeper, it seems that this mode will lock factory-overclocked cards to reference speeds for troubleshooting purposes. In the 378.49 driver, many Pascal cards incorrectly had debug mode forced on, something that could cause lower-than-expected graphics performance or interfere with overclocking.
The 378.49 release was also causing problems for players of the seminal block-building game Minecraft, thanks to a strange interaction between the driver and Java OpenGL applications. According to this post on the official Minecraft Reddit, the problem appears to lie with the driver's 3D Vision functionality. Users who decided to skip installing the 3D Vision component were spared the trouble.
The 378.57 hotfix driver should fix both of these issues, although a couple of users on the GeForce forums reported that they had to do a "clean install" to properly fix the debug mode problem. Grab the updated driver from Nvidia's customer support site.