I have CC 2018 running on windows 10 and I have not seen this behavior yet.
What I can recommend is a Preferences reset and this is very easy to do. It's the go-to for sudden glitches.
Another thing common to windows is graphics card/driver problems. You also go into Preferences > Performance and uncheck "Use Graphics Processor" to see if the problem goes away. It's a troubleshooting step and unfortunately disables GPU enhancements. You can dial down GPU performance to "Normal" or "Basic" in the Advanced GPU settings in Photoshop, as well as visiting the GPU Maker's site for updates to your GPU card's drivers in hopes of resolving the problem.
Worse comes to worse, reinstall CC 2017 and await bugfix releases to CC 2018. There has been many documented problems and hopefully Adobe can address them in the next release.
I haven't heard of this either. At first I thought that the mask might have been getting selected, which would change the foreground and background colors, depending upon what was selected, but not as novice users, I would assume you would have noticed that.
Nothing like this ever happened on my Mac or PC versions of CC 2018, Chuck. Use CC 2017 to get the work done and troubleshoot CC 2018 later.
A lot of odd keyboard stuff on the Windows side, but not on the Mac side. Alt + Delete (Mac's Backspace) works fine.
Since upgrading to PS 2018 we've found at least 7-8 bugs. And about as many in LR Classic CC. No solutions from Adobe so far.
The shortcut for changing active layers, alt + ] and the shortcut to add a layer mask, shift + F8 for me, are also randomly not working. Anyone having these problems?