(Solved) Can't play files that worked before update

The new AMD Crimson 16.1.1 driver should also work on your system:
http://support.amd.com/en-us/download/desktop/legacy?product=legacy3&os=Windows%207%20-%2064

LAV hardware acceleration disabled; I think you suggested that before. Downloading driver.

The AMD Crimson 16.1.1 driver is a beta that was released days ago (February 4, to be exact; that's right around the time everything went to crap). What a shame they didn't tell us all the ATI models were being deprecated. I've even got the Catalyst Control Center on here, trying to keep this thing going.

Budgets being what they are, I'm trying to squeeze every last breath out of this computer. Besides, we've seen Microsoft's business model... I won't trust Win 10 until 3 years from now when they work out most of the bugs!

Of course... "Catalyst Control Center: host application has stopped working." Yeah, uninstalling that sucker. It ate up hard drive space and ROM.

And here is a potential bump in the road: uninstalling Catalyst, and the old drivers. Read this thread, which I got from the AMD forum.
These guys are going at it hammer and tongs.

https://community.amd.com/message/2689157#2689157

Use the Display Driver Uninstaller tool mentioned in that topic. It should completely remove the driver. Then when you reboot Windows will use the standard Basic Display Driver from Microsoft.

You may want to test the stability of the system for a few hours with the Microsoft driver. If everything is stable, then you at least know the problems are purely AMD related.

So, if I understand correctly, this was caused by a confluence of events:
1) the update of the codec pack (which has never given me problems before); and
2) the deprecation of the ATI/AMD driver for this graphics card. AMD bought the ATI company, and this was their way of killing off the last remnants.

I've never understood why a graphics driver needs an update. If the card is to spec, and all the software is made for conformity to a particular OS, then the drivers should be stable forever.

Downloaded Display Driver Uninstaller. Now I'll have to wait until dark, while the family's not using the PC. Another midnight madness maintenance mission.

I don't think either of those events is related. The fact that you updated the codec pack around the same time is just a coincidence. There would have been more people with similar problems if there was a regression. If you install the older version of the pack, without doing system restore, then you should get the same problems.

It is not unlikely that a file belonging to the AMD drivers was also damaged. SFC only checks the integrity of the Windows system files. A fresh install of the driver (even your old version) could fix it.

Got a gap in the day, so I ran DDU in Windows Safe mode.
Got rid of all the Radeon/Catalyst Control Center stuff.

Then, installed the AMD Crimson beta driver.

Success! WMV, Flash, webm and mp4 videos; mp3, m4a, Ogg Vorbis and WAV files -- all play without incident in Windows Media Player 12.

Thank you for all your help, Admin. A virtual pint of your favorite beverage, on me.

Sometimes, it really is your piece of junk computer, or some issue with it.

I've been using K-Lite for 5 years, without incident.

There is something else, though. Sometimes WMP crashes if a K-Lite update is forthcoming, but afterwards there's no hiccups.
Is that due to driver issues, or is K-Lite trying to get my attention?

If an existing installation becomes unstable, particularly for files that used to play correctly, then it is an indication that something might have gotten damaged (like that broken file you had) or that another application made codec related changes. Re-installing the pack usually fixes such problems. Even if you use the same version.

But in any case, if you get any more crashes, just come here with the details, and I should be able to help.