If you have Power Management on your NT 4, SP4 Workstation, chances are that it no longer functions.
With SP4, a Windows NT Server function writes a time stamp to the the hard drive approximately every 5 minutes in order to approximate system shutdown time in the event of improper shutdown.
Unfortuneatly, this feature is turned on by default, even on a workstation. To disable it, navigate to:
With the Current Version key selected, Add Key name Reliability (unless already present) with a Class of REG_DWORD. Select the Reliability sub-key and Add Value name TimeStampInterval as a type REG_DWORD and set the data value to 0.
You will need to restart your workstation.