How to Identify a Registry-Breaking Font File

Hi all! Long-time Font Squirrel user here - the website was one of several that got me through my undergrad design courses, and I’m immensely grateful for that. So I thought this would be a good place to turn to for an issue I’ve been having for some time now and just dealing with rather than taking the time out of my busy routine to sit down and fix it.

Some time last February, I ran into a bug that turned all the Windows display fonts into empty boxes and wingdings. So to even be able to read the File Explorer, I had to go and reinstall all the Windows default fonts, and then all my other fonts. When I took it into my local IT help, they said one of my font files must’ve broken my font registry, and copying over the font registry from an unaffected computer would fix the issue - and it did. But, being in class, needing my font files and having no idea which file was the culprit, I had to reinstall them all, mess up my registry, and keep putting up with the Reboot Wingdings.

My question is this: does anyone know how to go about determining which font file is the culprit? Or at least mass-testing them to find any corrupted files. The brute-force method I can think of would be to test each one individually by re-fixing my registry, installing one file at a time, rebooting and seeing if it ends up broken again, but I have over 1000 files I would need to test and obviously, that would eat up a lot of time. I’ve weeded out a few corrupted files already by just previewing them in File Explorer and seeing which won’t open, but if there’s any more thorough test that can be done, I’m not aware of it, and I won’t be able to go to IT Help and ask them 'til the day after tomorrow at least.

I use a Mac, so I can’t respond to the Windows issues. But I use Monotype’s Font Explorer, a font management utility. It’s available on both Mac and Widows, and it is well worth the money. It lets you do many things, such as making sets of fonts, previewing the entire glyph set, viewing metadata like publisher and vendor, among many others—including identifying defective fonts. I highly recommend it or any font utility.