If the message appears at startup as you say, that suggests that for some reason, an entry has been written (erroneously) to the registry to run the unwise.exe file every time Windows 2000 starts.
Try disabling the entry from startup.
Windows 2000 does not have the msconfig utility as in most other Windows. If you have some startup manager installed, use it to disable unwise.exe from startup.
If you do not have a startup manager, download Mike Lin's Startup Control Panel, which is small and easy to use. click here
After you install it, go to Control Panel, double click the "Startup" icon. Select the various tabs one by one, until you see an item showing "unwise.exe" either under the name column, or the path column. Most likely tab is the HKLM/Run tab.
If you find it, untick the relevant box. Click OK. Restart the computer to see if the message appears again. Hopefully not.
If things continue to work fine (give it some time), you can go back to the item in Startup Control Panel, right click the item and select delete. Then go to the Delete tab and delete it from there as well.
There may be more than one application using its own unwise.exe for uninstalling itself. So don't delete any unwise.exe file you may find on your computer rashly.