Half of system functions freezes

Question

It happened to me more than thrice that suddenly, usually while browsing the Internet (with Firefox), a page freezes in the loading state, without ever finishing loading. No network issue is reported.

Then, my Skype completely freezes (edit: but yesterday it didn't do so), although Steam works still fine, and I can send and receive messages there. Although I can still launch processes, after a while, no additional processes can be run at all, and Process Explorer stops updating the process list. However, I am still able to close frozen applications (including Explorer), open windows of (some) previously started processes, and kill processes via Process Explorer. Programs which can still run are also able to open files. Even when I close all possible applications, the problem still persist, and even attempting to shut down the system or logging off does absolutely nothing. Only switching users does something - turn my screen black forever.

Eventually, I am forced to hard restart the computer, as even the power button on the computer doesn't send any signal to start shutting down the system.

I haven't noticed any process taking too much CPU in Process Explorer during the issue.

There were no updates to the system recently, aside from regular Flash, Java, and Avast updates (Windows Update is turned off), and also one NVIDIA update, although I think the problem may have started before it.

Edit: Just after downgrading NVIDIA to a version from February 2015, it happened again, though Skype didn't freeze this time.

Answer 1

One thing an anti-virus or security program might do is hook into the Windows program launching process to check files that are being executed. If something has gone wrong here, it could cause the system to hang or no new programs to be able to launch.

Try temporarily disabling Avast and see if the problem is reproducible. If so, update or switch anti-virus programs, or diagnose further from there.

Answer 2

Run Prime95 on default Stress Test settings for 10 to 20 minutes to see if any of the workers fail. Run HWMonitor simultaneously to see if you're overheating. A worker failing or producing an error is the worst-case scenario and indicates hardware failure in one of the big-three: CPU, Mobo, or RAM. Overheating is usually a simple problem to solve.

If not that, then:

System Restore Point

If not that, then:

I see you've already checked for obvious disk failures, but perhaps a block is having read issues, which wouldn't necessarily trip SMART. Look at your HDD manufacturer (you can find it in device manager; a model no. starting with WD is Western Digital and ST is Seagate, for example) and get your manufacturer's HDD diagnostic tool from their website (Seatools even makes a CD image you can boot directly to for repairs). Run it, and if it offers to repair blocks for you, let it.

If not that, then:

Check for integrity violations in Windows with an administrator command prompt, type: "sfc /scannow". If that fixes it, awesome, but if not, the final step (for your situation) is to reinstall Windows and see if the problem recurs. I recommend deleting all partitions (which deletes all data!) when you're installing just in case one of the file systems is causing part of your issues. You could instead install Windows 7 onto a spare disk and use that for a few days to see if the problem recurs, leaving your current installation intact while you experiment. But, that is just a delay tactic and this sounds so low-level as to warrant the nuclear option to save time.

Answer 3

Since according to what you say display freeze didn't happen before, and the only significant system change was the Nvidia driver, it is worth trying to downgrade to the previous driver version.