Alright, so it's still unclear what the possible cause is, but the assumption are so far are either your graphics card (which would require an update) messing the text up or the font file being corrupted (in which case you would need to redownload the font and check if it's working as normal in other programs). I require more information based on this problem.
- Does a similar issue occur with games of the same engine? We used Ren'Py to built it.
- Does Anti-Virus detect any files as malware and thus deletes any of the files?
- Is it just the menus or also the ingame text and narration?
- Is anything else weird or broken in some way?
Depending on the issue, I might have to ask more questions later.