Use ext3's method to get into Safe Mode. You will have to navigate with the Arrow keys and use the carriage return to select your required option.
If you have not run a defrag for a while it could take quite a while. Like 4 hours or more!
There is a huge range of opinion as to how often you should defrag. I run it on the last Saturday of the month, whether it needs it or not. W'98 with K500 and 30gb Hdd. In just start it running and go and do something else. I no longer know how long it takes but it has usually finished before I get back.