Description:
Some of my applications are running in a weird low-resolution mode. When the affected programs are open, the icons on my taskbar reflect the low-resolution. If the program is closed, the icon is displayed in normal high-res.
At first it was just Chrome that I noticed. But I closed iTunes at one point and when I re-opened it, it was low-res too. Slowly I would notice other affected programs: the list came to represent Chrome, iTunes, uTorrent, and Steam. All others worked fine.
Chrome displays an additional symptom: Youtube, when full screen, doesn't cover the taskbar.
TL;DR
Various programs started running in low-res while the rest of the OS (including other programs) look fine.
Best Answer
The Windows 7 control panel's display settings were set to zoom at 150% (my display is at 1920x1080 on a TV about 10' from my couch, making text hard to read).
These settings were changed when most of the affected programs were open. As a result they didn't begin to misbehave until I had closed and re-opened them (this doesn't happen very often). By then the settings change had been forgotten about and I didn't think of it as a cause.
By right-clicking on the affected exes, I was able to Troubleshoot Compatibility and follow the wizard where I selected the issue Program does not display properly when large scale font settings are selected which then applied Scaling on High DPI. This solved the problem for the specific application and must be done for the others.
Alternatively, change the zoom settings back to 125% or 100%.