I'm experiencing this exact same issue since upgrading to the 980 Ti on Monday. My rig loads windows usually within 4-5 seconds, & still does, but now applications/task manager/Windows Explorer are deathly slow to respond on start up. Event logs say error with kernel pnp, drivers here & there. All related to NV's latest driver one way or another.
I'm really tired of the screen going black while using Chrome when the driver crashes, & the only way to get it back on is to reset & pray, or clear CMOS. -_____- This really is so ridiculous. Nvidia, stop acting frail.