sorachi-jirachi:

It seems Paint Tool SAI does not like Windows 10 at all, because when I tested it on the beta version of Win10, it wouldn’t run at all. If you use SAI as your main drawing program and wish to continue using it, then I strongly suggest you avoid upgrading to Windows 10 until somebody finds a way to get it to work on there. It’ll be a real bummer to see anybody having to struggle with the loss of SAI because of a Windows upgrade that it’ll refuse to work on.