There are several places that may have a legacy call to a non existent Ranger UNC path.
As Strawberry suggests the profiles are one place, but don't for get login scripts, GP's and the Local Machine Default User!
The scripts, pretty obvious and easy to trace.
The GP's watch out for software installation calls to a legacy path \\myserver\ranger\xxx this extends to folder redirections and all sorts that may have been created by others (not Ranger)
The default user profile, of course this gets imaged between machines and it only takes a simple app or utility to have been installed that points to the now redundant UNC path.
What you really need is a packet capture of an affected PC from startup to login.
Unfortunately you will need a network tap or monitor port on your switch to do this.
Set up the tap, configure Wireshark/Netmonitor whatever tool you like to capture the packets.
Startup the affected machine and login as usual.
Your capture should reveal any calls to the rouge node or unavailable UNC that is affecting your login.
I fortunately have a tool for this, an in-line network monitor so it's not that labourious.
When I've removed Ranger I've simply uninstalled it from the server it was installed on, (which should restore it to a native Windows 2003 domain). I then re-image all machines as Ranger does leave a lot behind and secondly, it allows you to get machines to a level you want in terms of security and applications.