If you are developing a windows service with .net, when you try to uninstall and re-install your service in a Windows 2000 machine, you might get an error saying “The specified service has been marked for deletion”. This is listed as a known issue with Windows 2000 based machines by Microsft.
Trick is to re-start the machine before you try to re-install it.
For more details refer to this Microsoft link: http://support.microsoft.com/kb/823942
Note: To install/uninstall a windows service (developed using .net), you use installutil.exe