Since ComicSans is a built-in OpenType font, I would suggest running a system check for errors. You may have some corruption of your Windows install and or the font cache which is preventing this font from loading properly.
You might want to try a System File Scan.
- Open a command prompt with system (admin) rights
- Type SFC /scannow and press enter.
This can find and sometimes repair/replace missing files in your operating system.
Reboot after running this to find out.
John