Clear System Font Caches
Anyone who supports graphic designers learns to hate fonts. As tiny pieces of software loaded directly into the operating system, they're responsible for more than their fair share of system issues. So it goes with users whose systems freeze up on login, displaying nothing but their desktop background and a lonely spotlight icon in the upper left corner of the screen. The issue is so common, there are a myriad of third-party tools to address it. And like so many common problems, this one comes down to fonts again.
Faced with a machine that consistently lets users log in, but get no further, the problem is very often a corrupt font cache. This causes the system to have issues rendering type, prevents the menu bar from displaying properly, and therefore stops the login process before the user can take control of their work environment (even after reboot). The issue is especially common in later versions of Tiger, but it plagues Leopard systems as well. One way to correct the problem is to boot into single-user mode and clear out the system's font caches entirely.
Reboot the machine while holding down the "Command" and "S" keys. If the frozen workstation runs Tiger, type:
rm -r /Library/Caches/com.apple.ATS/*
If the frozen workstation runs Leopard, instead type:
atsutil databases -remove
Replace USER with the name of any administrative user, and MACHINE with the hostname or IP, belonging to the workstation. You'll be asked for that user's password, after which these commands will remove the Apple Type Server caches from the frozen machine, and with them this issue. If you can login as an administrative user, these commands can also be run from the Terminal by preceding them with "sudo". You can then safely restart, and login (as well as fonts) should function normally again.
Special Thanks: We were reminded of this problem (and its Tiger-specific solution) by Aaron Robinson, systems administrator at Seattle's fine Hornall Anderson Design Works.
Recommended Reading: For more information on corrupt font caches (and some products to clear them without the command line), you can check out the CreativeTechs QuickTips blog.
