Windows explorer can get hung up sometimes in strange ways but it's not really a problem. If you have something like process explorer or even default task manager you can just kill the explorer.exe task and then use "create new task" and type in explorer.exe to start a new one.
If you ever find yourself in a situation where explorer won't work you can use the command line cd and then dir command to list files and del command to delete to remove stuff. You can also use an alternative graphical file manager for windows like total commander that shouldn't have the same issue. Sometimes it's a thumbnail loading issue, in fact it often is.