Well... I have some comments on this.
First of all, we
absolutely need to have a way to see this information.
I think one file may have some sort of permissions issue, and the others are just 'backed up' by this one file being 'stuck' for some reason.
I have quite a bit of experience with this. If you see this indicator hang, and stick on files, it means one of three things about the files themselves (and/or their associated sidecar XML files if they're video files and have this enabled):
1. They are in-use. Either by Media Center itself (playing the file), another client copy of MC (JRemote, Gizmo, etc) elsewhere on your network, or by another entirely unrelated application on your computer or network.
2. Media Center's process (the user you are running it as) does not have adequate permissions to write to the files. The filesystem isn't granting access, and MC keeps trying (waiting and hoping, really) to get access. This process is multithreaded (in my experience) and does not get "stuck" with more in queue. If it lists five files, then five files are read-only or inaccessible for some reason.
* The files themselves may be read-only (or in unusual circumstances on a read-only filesystem of some kind). Note that folders themselves use the Read-Only NTFS attribute for another purpose, and cannot be "read-only". The filesystem only obeys the read-only attribute for files. However, in Windows explorer, you
can apply this change globally to a whole structure of files by changing it on a parent directory. In Windows Explorer, open the Properties dialog for a parent folder and uncheck the greyed out Read-Only box. It will prompt you to do it only for that folder, or recursively across all sub-folders and files. However, if you suspect filesystem issues, you should probably check ownership and filesystem permissions
first (and then come back and uncheck the read-only box if needed). That's because if you don't have permission to access the files, you won't be able to modify the read-only attribute for those files either.
* You may not own the files, or have proper permissions to access the files on the local filesystem. This can occur if you use your PC with multiple users (so some user accounts may own different sets of files, and they may have their own permissions depending on where and how they were created). It can also occur if you migrate data from another PC (perhaps restoring from backup after a reinstallation of the OS). It will often, in these cases, manifest with the file or directories being shown as owned by (or having permissions listed for) a big GUID string, rather than a username. Windows shows the GUID for files owned by a user account in the filesystem that does not have a matching named account on the currently booted OS. If you have this, you need to take ownership of the files and make sure your user account has full control permissions over the files, and their directory structures. I often find it is the folders, and not the files themselves, where this goes astray under Windows.
* Likewise, if the files are stored on a NAS or other network storage device, your user account needs to have full read and write access to the file share. These permissions are combined with the filesystem permissions, so your user account must have permission both places to be able to write to the files. Many of the "easy turn it on" modes of SMB sharing in Windows do not enable write permissions for shares, and they can be confusing to set properly with embedded NAS devices, so it is worth checking over thoroughly. This can also be an issue if you don't use the same username across different PCs in your home and are trying to access files over the network. Without an Active Directory server, Windows relies on the Username matching (the short one) to determine if a particular network user is the "same user" on the filesystem itself. Internally (for local users) it uses GUIDs.
One good test, is to just try to do something with the files externally from MC. Open up the folder in Windows explorer, and try to create a new text file in the directory. Rename it. Delete the file then, and make sure that works. Move one of the media files in question (or the whole lot) to your desktop (not copy, move), and then back again. If you can't do it there, then MC can't do it.
3. Anti-Virus or Network Security Suites could be blocking it, or slowing it down so much that something gets angry and times out and hangs. Manipulating network files, in particular, is already pretty high-latency compared to working on a local filesystem. Adding on-the-fly AV to your already-slow network volumes can be very troublesome, especially over WiFi. Add exceptions, especially if the files are isolated in a "known good" media library location. Those files are your files, they're safe. Spend the resources scanning the actual exposure points (new downloads, email attachments, temp locations, user directories, etc).
4. A MC process itself could be stuck. This most often occurs if you have damaged media files, including ones that were corrupted in an aborted write during an unplanned power loss event on your computer or delayed write failure, for example.
In any case, it is not something that will typically go away on its own (unless the files are really in-use, and then it will when they're no longer in-use), and you should take steps to address the issue. Because those files are (unless in-use, again) broken and inaccessible in some way.