3.3.4 Palettes displaying wrong graphics (some doubled onto others) [SOLVED]

Just updated from an early stable MuseScore 3.0.1, to latest stable one: 3.3.4.9066 (Rev. 7684abe).

Program start is unstable at clean startup. The ‘New score’ pop-ups cause freeze. That can be done away with by starting empty, but then the top menu freezes, palette has graphics freezed/empty/“see-through” and program has to be forced shut down. In effect, forced startup from *.mscz goes seemingly OK; goto main problem.

Main problem: PALETTES, bad from start with new version: Even when functioning underneath its graphics, many fields display wrong graphics, mostly where a correct graphic is “copied” onto its left neighbor field, both still showing correct pop-up labels when hovered over. Correct graphics can be fetched by right-clicking ‘Properties’, then ‘Cancel’ (‘OK’ does not work), but it is simply too much and has to be repeated for each field at every startup. It seems the error is worsened by toggling ‘Basic’/‘Advanced’, but it is there with ‘Basic’ from start.

Several ‘Revert to Factory Settings’ has had no effect, other than having entire program actually crash at restart after completing factory settings wizard.

Windows 7 Home Premium SP1
Location: Sweden (still not listed under keyboard layout)