How to make barcode font display correctly in web service

Just got an issue when using barcode font in a web service hosting in IIS7. The barcode font can't display in the document which is generated inside the web service. And the solution to make it work is setting the option "Load User Profile" of IIS 7 application pool to True.

Creating IIS7 sites, applications, and virtual directories

This is a post about configuring IIS7:

Creating IIS7 sites, applications and virtual directories

This is about the new command line util in IIS7: AppCmd.exe.