iTunes has a limitation that you can only run a single instance of it at a time. When you install iHomeServer there is an option to either install iHomeServer as a Windows Service or as a Desktop application. If you chose the former, then you get the advantage that iHomeServer will start iTunes up as a Windows Service so it is running all the time, even if nobody has logged into the computer's desktop. However, as you have seen, because iTunes is running in the background, if you do log into your computer you will get the error message you quoted if you try to run a second instance of iTunes on your desktop.
There are a couple of features built into iHomeServer to help you work with iTunes when it's running as a background service:
1. The iHomeServer Management Console lets you do many of the library management tasks you would do through the iTunes User Interface. You can run this on the desktop (or even the desktop of a different computer for remote management) even when iTunes is running as a Windows service. The user interface lets you do many additional things that aren't possible through the iTunes application interface such as search for metadata/artwork for movies and television shows, manage watch folders, rip DVDs, etc.
2. However, there are things you want to do in iTunes that you can't do from the management console. iHomeServer provides a tray icon that lets you switch iTunes from running in the background to running on your desktop. So instead of double-clicking the iTunes icon, go to your tray icon and find the iHomeServer icon. Left click it and select 'Open on desktop'.
Finally, if it isn't that important to you to run iTunes as a Windows Service but still want to leverage iHomeServer's other features such as watch folders, DLNA server, web access, metadata management etc, then you can re-install iHomeServer in Desktop mode. In this mode, iTunes will not run as a service, but can be opened manually on your desktop. When iHomeServer detects that iTunes is open, it will hook into iTunes and provide its additional features.
Have a look at our user guide for further information:
Installing as a Windows Service vs installing as a Desktop application: http://www.bizmodeller.com/iHomeServer/ ... lation.htm
iHomeServer Foreground / Background switching: http://www.bizmodeller.com/iHomeServer/ ... tching.htm