I'm using Windows 10 with dual monitors, both of which are set to show my taskbar. This problem recently just started, seemingly by itself:

The time display at the right of the taskbar (both of them) is unreadable.

My taskbar is black, with small icons. The time display seems to be there, but in black. When I mouse over it, I get the date display above the taskbar, and the taskbar portion (the time) shows up in black on a dark gray background. When I click it, I get the large time and calendar display.

When I turn off "Use small taskbar buttons", the time display shows up fine in white.

Who can help me fix this?

FYI, I have another taskbar issue that seems to be connected with Excel, but might be related to this one: When I have multiple documents open in Excel, mousing over the taskbar icon just shows a miniature view of one of them. I have to click the Task View icon to see them all.