After a lot of futile trial and error, the only way to get version 3.0.5 of Mozilla's Firefox browser on my PC was to uninstall version 3.0.4 first.
Utilities Updates: Deep Freeze Mac ARD 3.21.070.0167; ImageWell 3.0.5; SmartBackup 2.0.2; more
Utilities Updates: Tiger Cache Cleaner 3.0.5; Adobe GoLive CS2 8.0.1; Butler 4.0b27; more
Utilities Updates: Snard 2.4.1; Samba 3.0.5; SafarIcon 2.1.2; StatusMonitors 1.3; more
Utilities Updates: DockExtender 3.0.5; CodeTek VirtualDesktop 2.3.5; Xupport 1.3.4; SafeFile 2.0B4; more