Since Windows NT was originally released several bugs and security holes have been discovered. (There were several known bugs in the software when it was released but these bugs were left because they were not considered Show Stoppers.) In order to solve these problems and increase the functionality of NT, Microsoft will occasionally release additional add on software.
When a problem is first discovered and resolved Microsoft will release a software patch called a Hot Fix. When enough patches have been released Microsoft will group them all together into a service pack.
When you install a Service Pack it gives you the option to create a backup copy of the orginal files. The only way to uninstall the Service Pack is to select this option. I have seen some software applications that will not install if a service pack is installed. For this reason I would encourage everyone to select this option and create a backup copy.
Windows NT is currently on Service Pack 3 and there are several Hot Fixes beyond this. Service Pack 3 incorporates both Service Pack 1 & 2. Service Pack 4 is scheduled to be released in June or July of 1998. The Service Packs and hotfixes can be downloaded free of charge from Microsoft's FTP server at
The patches should always be installed in chronological order.
Service Pack 3
ASP fix (only on machines running IIS V3.0 with ASP 1.0B)
DNS fix (only on machines running the Microsoft DNS service)
IIS fix (only on machines running IIS v2.0 & v3.0)
GetAdmin fix (file named admnfixi.exe, replaces dblclick-fix, java-fix and an older getadmin)
Winsupd fix (file named winsfixi.exe only on machines running WINS Service)
SimpTCP fix (file named chargeni.exe, replaces an older simptcp.fix)
ide-fix (only on machines with IDE/ATAPI disk drives)
IIS4 fix (only on machines running IIS v4.0)
teardrop2 fix (replaces icmp-fix, land-fix, oob-fix and tearfix)
pent-fix (only on machines with Pentium and Pentium MMX processors)
lsa2-fix (includes LSA fix)
priv-fix (fixes a new security bug)
y2k-fix (year 2000 fix)
The fixes that are printed in bold letters above are related to security holes or situations that will result in system crashes. These bugs are common knowledge on the Internet. These fixes should be installed on every system.
After you install new software or modify the NT services it is highly recommend that you reinstall the service pack and all of the hot fixes. The reason for this is that these changes may have caused the system to revert back to an earlier system file and there by compromised the fix.
There is no easy way to tell if a fix or the Service Pack has been compromised. If you want to find out what hotfixes have been installed on a system in the past, you can download and run "hotfix.exe" from Microsoft.