Upgrading IE on NT4.0

Does anyone remember if there are any known problem upgrading from IE 4 to IE5.5? When I upgrade I get a message saying “Cannot upgrade with current network setting changes have been made system will reboot”. The system reboots and the problems begin. I get Dr. Watson errors on Explorer.exe about every 30 seconds and I can no longer run most things ( windows explorer, my computer etc.) the only solution is to reinstall NT and start again.

I seem to remember that when upgrading certain version of IE you had to remove the older version first, but I can’t find anything about this anywhere.

Thanks in advance for any help.