I have had this a few times now. If I install the IPaddress tracker the installation tries to use a users share that does not actually exist \\<server>\users\<username>\ if this share does not exist then the installation fails. On an SBS2008 server as standard the users share folder is actually called redirectedfolders.
You can get around the problem by creating an additional share on redirected folders called users. When you do that the installation succeeds and IPTracker works correctly. If you subsequently remove the share it will 'lose' its records and fail when you try to create a subnet.
I have looked in all the ususal places to see where it is getting the 'users' share information from but I am unable to find it.
It is not a great work around to create this additional share if I can avoid it