I'm using a Samsung 840 PRO 256g SSD and have loved it for the year I've had it so far. I would have boot times of like 10 seconds. But starting this week it has slowed to a halt. Taking 2-3 minutes to boot. It seems to hang on the "Starting Windows" part of the boot for most of the time, and then sometimes it'll go past the "Starting Windows" part quickly, and then hang on a black screen. I've done a windows update this week, I installed a new update from Nvidia for the graphics driver. I unistalled the driver and used a driver cleaner and reinstalled and that hasn't changed anything. This is the only time I experience problems though. Once I'm on my computer, everything seems normal.
Thanks.