I think that this may happen with some old antivirus that are opening and trying to scan files stored in a directory before they are completely finished. When the download ends, the file is closed and the antivirus takes an immediate shared lock on the new file to scan it, preventing the file from being moved.
This problem is not specific to LimeWire and affects other downloads performed in Internet Explorer as well, when it downloads a file to a temporary folder before moving it to the target directory when the download completes. It also affects some FTP clients, and many other softwares that create temporary files before moving or renaming them when the file is complete.
Better try a newer version of the antivirus without this very limitating bug, so that it will scan the files on the fly (while the file is opened and being written) without taking a shared lock on it only after the file has been closed by the application creating or modifying it -- at least an antivirus should scan the file while the application is currently closing the completed file (and the application should then be blocked during the file-close operation until the antivirus scan completes).
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A shared lock, even if it allows reading the file from other competing applications, prevents any attempt to move, rename or delete the file unless you are using a Unix filesystem where a file can be unlinked from all directories despite it is still active and opened in some applications; this is a great tool to allow easy software updates, but also a security issue as this means that Unix will not prevent all files from being deleted without necessarily hanging your system, but the next time you will reboot, all files will have been deleted. Unix avoids this caveats by allowing you to restrict writes on directories so that files they contain can't be renamed, moved or deleted, despite the files can still be modified independantly of the directory permissions... |