Notes about the WD3 file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The WD3 file type is primarily associated with 'Offline Explorer' by MetaProducts Corporation. MetaProducts Offline Explorer is a Windows 95/98/ME/NT/2000/XP/2003/Vista off-line browser that allows you to download an unlimited number of Web and FTP sites for later off-line viewing, editing or browsing. DESCR.WD3 files reside in each directory Offline Explorer creates and contain information regarding all downloaded files in the directory. They are bound to the directory where they are located and they contain the information used to update files from Web sites and their MIME types. So, it is commonly safe to remove them when you move the downloaded sites to another directory.