Since moving from dial-up to ADSL the Disk Defragmenter utility will no longer run to completion. Disk Defragmenter starts but continually starts again because the drive contents have changed. My guess is the problem is related to ADSL modem hanging off the USB port. The computer is running Windows 98.

Disk Defragmenter is a very sensitive application towards drive contents changing during operation. This is because Disk Defragmenter reorganises the data on the disk. Files are not stored as one entity, but are instead broken-up into many chunks. These chunks are stored all over the hard drive, so when that file needs to be opened the computer must find all the chunks in different places on the drive. This is called fragmentation. Disk Defragmenter reorganises the drive so continuous data is placed in subsequent locations on the disk, so the chunks for each file are located together. The net result being accessing data is much faster. However, Disk Defragmenter cannot operate while other programs are using the disk because the configuration of the disk is changing, forcing Disk Defragmenter to restart. Since your ADSL connection and modem are likely to be operational most of the time, it is probable that data is being accessed and written to the hard drive, causing interruption for Disk Defragmenter. I generally recommend that all users run Disk Defragmenter through Windows Safe Mode. This mode will not load any non-essential programs or drivers/devices (e.g. ADSL modem) so there shouldn’t be any interruptions running Disk Defragmenter. To boot into Safe Mode, restart the computer and after the power-on self test when ‘Starting Windows 98′¦’ is displayed (just before the Windows splash screen) start tapping the F8 key. The Windows boot menu should appear. Select ‘Safe Mode’ from the menu and press ENTER. Once Windows has finished loading, run Disk Defragmenter. When you are done, to boot Windows back into normal mode, just restart the computer.