These problems are caused by a bad context menu handler. Observe when the problem occurs. While right-clicking a particular file type? While right-clicking Folders? While right-clicking all file types?
If any of the symptoms occur when you deal with a folder, then you may need to inspect the context menu handlers loaded in these areas (AllFileSystemObjects, Folder, Directory). If it's only for a .txt file, inspect the file class of .txt file (HKCR\txtfile). Open Registry Editor and backup the selected branch, delete the context menu handlers one-by-one.
If it looks complex, download Shell Extension Manager to determine the Context-menu causing the problem. The ShellExView utility displays the details of shell extensions installed on your computer, and allows you to easily disable and enable each shell extension.
More details here - Right-click is slow or weird behavior caused by context menu handlers