I installed Kubuntu app. year ago. Everything worked nicely. However recently a weird thing happened - text in all applications spontaneously changed to unidentifiable mess (numbers, special symbols, Asian characters, etc). The process of change looks like when the system language was changed but it is affecting all text even in emails. After restart everything is back to normal. It has happened twice under standard user account. I have not seen anything similar with other accounts. If it is windows I'd say a virus, in Kubuntu maybe a bug 
but I cannot find anything about that.
Thanks
but I cannot find anything about that.Thanks