Mac OS 9.0.x: Startup freeze linked to fragmented drive

There is an ongoing debate among Macintosh users as to whether defragmenting a drive is really worth the bother. Well, here is one case where it definitely is! According to Apple TIL article #25145: In certain circumstances a hard disk with Mac OS 9.0.x installed can become extremely fragmented and fail to start up. When starting up you may see the "happy Macintosh" icon, but then the computer stops responding. This may happen if your hard disk is nearly full, or if you have a very large number of files and constant file activity, such as a busy AppleShare IP server running Macintosh Manager. Defragmenting the disk is a work-around, although the problem may return. Other solutions, covered in the article, involve reformatting the drive.