I have found the same questions elsewhere but the topic seems to be dead.
I keep getting empty color ramps, symbols and styles in ArcMap. I've attached a few screenshots that explain this.
Deleting Normal.mxt in "C:\Documents and Settings\#USERNAME#\Application Data" does do the trick... for 5 minutes. I have not found what causes this issue but it gets really frustrating. I have to manually color pick every single color over and over again, just because I don't want to close everything, delete the file, then open again just to change one or two color ramps and then need to do this all over again.
I have tried repairing and reinstalling ArcGIS, but nothing helped in the long run.
I am using:
Windows 10 Home (64bit)
ArcGIS 10.5 (student licence)