A bit of a weird one this, but I've found that Excel 2010 (pre-Windows 10 upgrade installation) doesn't work properly with anything other than English set as the default language. The way in which it doesn't work is even different depending on the language!

With English as the default language: Excel works fine.
If I set the default language to German: it crashes every time I try to print.
If I set the default language to Welsh: bold, italic and underline commands (whether from the keyboard or task bar) do nothing at all and changing a cell's colour gives it a completely different colour to the one selected.

These issues are consistent with each language setting following restarts and logging out and back in again.

Any ideas why this would be happening?