My company recently had 2 users and 2 documents say that they were missing the font Arial (.OTF) when they were opened. These were both files that had been created on their own machines and no other users had made changes or additions. Both users have the Arial font installed (.ttf) but this is different than what InDesign was requesting. Both users are using Windows 7 pro x64 and have InDesign CC 2014 v.10.0.0.70 installed.
They were eventually able to replace the font with another and save to correct this but it took several tries before the error stopped. I have not found anyone else mentioning this problem online. Is it more likely that error that both of these users experienced was due to a bug or glitch in InDesign or due to a corrupt font or file?
Probably caused by a mismatch in the version of Arial between users.