Hold down the space bar after you hear the Macintosh startup chime. This will bring up the Extensions Manager right after the Welcome screen and before it loads any extensions and control panels into memory.
Once the list shows up, scroll down until you see that particular extension and uncheck it. Once it's unchecked, just close out of the window and it should load all of the other extensions minus the offending on. If by chance you get the same error with another extension or control panel, repeat the same process for that particular extension/control panel.
• Apple iMac G5 17" (2 GHz G5) - Mac OS X 10.5.8/Ubuntu 10.04
• Asus Eee PC 901 (1.6 GHz Atom N270) - Fedora 13
• Apple Macintosh Quadra 650 (33 MHz MC68040) - Mac OS 8.1
• "JHVH-1" (2 GHz AMD Athlon XP 2400+) - Slackware 13.1