The name specified for at least one of the files in the archive is not a valid Windows filename. It may include characters that are not allowed in Windows filenames, it may be too long, or it may contain a name that is reserved for a system device such as the printer. WinZip® will not be able to extract the file using the name as it is specified in the archive.
WinZip does not list files with invalid names in the main window because it cannot predict what will happen if you attempt to extract the file: the result depends on the filename, the archive format (Zip, ARJ, etc.), and other factors. Therefore if you were to attempt to (for example) view the file, WinZip would not know the name under which the file had been stored and could not successfully open the extracted file or delete it after viewing.
Although WinZip will not automatically extract the file for operations such as viewing, you may be able to extract it manually. Just be aware that the extraction might not be successful and that, if it is, the filename on disk will probably not be the same as the filename specified in the archive. To try this, simply extract from the archive using the Extract dialog box, making sure that you choose All files in the Files area. WinZip will attempt to extract all files from the archive, including those with invalid filenames. Note that external archive utilities such as ARC, ARJ and LHA may handle invalid filenames differently from WinZip when they are extracted.