Windows 2000p Service pack 4

Have downloaded service pack 4 for windows 2000 P on my
home pc

Had set up 4 users as follows

Administrator (Me)
Young son as Power user
Elder son as Power user
Wife as normal user

Since have installed service pack 4 on pc me and younger
son can use internet explorer and all the desktop icons,
but when others try to click on any icons on desktop or
try ie for internet access they get following error message
You get when windows error occurs with grey box with
following on it

Microsoft Visual C++ Runtime Library
X Runtime Error
Program c:\winnt\explorer.exe
This application has requested the runtime to terminate it
in an unusual way
Please contact the application's support team for more info

Internet Explorer is version 6.02:2800.11061s
ID Update version
sp1;Q813489;Q330994;Q818529;
This is a customised Version of IE

Hope you can please, please, please assist as it is
driving me up the wall not to mention the wife and kids
too!!!!!

Your assistance is greatly appreciated

Regards

Sam Davda