Does turning off »Use Graphics Processor« in the Performance Preferences and restarting Photoshop have any bearing on the issue?
What else have you done for trouble-shooting so far?
No, it doesn't...
There were no problems with system or Adobe. One day menu appeared half of it's size, after few weeks agian and since 3 days there there is just one pixel line.
It's affect this menu only, other ones work proper.
Try resetting your preferences.
well.. as I wrote before:
"Reseting preferences and even updating to 2017 version did NOT restore to oryginal size."
I've been trying all of things you suggest and all in vain.
This is strange situation coz it didn't happen once rather progress issue.
Is it sth like script or *.dll files which could be replaced or fixed?