I updated to Mavericks yesterday, before doing this i backed up my fonts by going into Font Book, right clicking my User collection and exporting it... After the install i went back into Font Book and dragged my User folder into Font Book... i'm assuming this was a big mistake. It started throwing errors about duplicates and lots of fonts were disabled. Every font went into the All Fonts / Computer collection and not into a User collection as i expected. I'm now left with an absolute mess so i attempted several things like getting font book to fix duplicates and errors and also tried 'restore standard fonts' Nothing seems to work and now photoshop is completely borked... Any file i try to open it gives me an error: Selected font failed during last operation. If Problem persists, please disable the font. If i try to start a new document it says: Could not complete your request because something prevented the text engine from being initialized. I've got clients bugging me for work and i can't do any of it. Any suggestions here? I'd love to be able to go back to the original settings (before i touched font book) then just start adding fonts manually.