I figure this could potentially end up with enough conversation that it'd clog the generic computer thread, though I'm mostly just posting to see if there's an immediate and obvious explanation before I start delving into dedicated tech support sites or swapping out components etc.
So, over the past month I have had 5 occasions where on turning my PC on it goes through the normal bios post process with no apparent issues, but when it gets to the Windows 10 loading screen it appears to get 'stuck' - it sits there with no spinning white dots, no disk activity, and the caps/num/scroll lock keys no longer toggle the related keyboard LEDs. Normally it only sits at the windows loading screen for a second before it transitions to the windows login screen (I have an SSD as my main drive), but when this happens it can sit for several minutes with no obvious activity.
On each occasion I ended up hitting the reset button, at which point it boots up normally and reaches Windows in the usual time. Except for one thing - the system time is showing the time it last shut down rather than the current time. If I leave it a while it auto-updates eventually, or I can go into the time settings and manually force an update.
There's not been any other apparent system instability and 90-95% of the time it boots up fine (which makes troubleshooting a bit trickier since it could be days or even weeks before it occurs again). The system time bit makes me think CMOS battery, but googling on that doesn't seem to suggest it would cause the loading lockup issue (and similarly there's plenty of results for windows getting stuck loading - mostly relating to windows update - but not so much coinciding with system time not updating).
If necessary I could post system specs and there's some maybe-relevant stuff in the event viewer, but I didn't want to clog up this initial post with more wall of text than necessary - I mostly just want to see if this jumps out as immediately recognisable symptoms to any of the more technically experienced members here.