Wikipedia
ExploreZip, also known as I-Worm.ZippedFiles, is a destructive computer worm which attacks machines running Microsoft Windows. It was first discovered in Israel on June 6, 1999. Worm.ExploreZip is a worm that contains a malicious payload. The worm utilizes Microsoft Outlook, Outlook Express, or Exchange to mail itself out by replying to unread messages in your Inbox. The email attachment is Zipped_files.exe. The worm also searches mapped drives and networked computers for Windows installations. If found, it copies itself to the \Windows folder of the remote computer and then modifies the Win.ini file of the infected computer. On January 8, 2003, Security Response discovered a packed variant of this threat which exhibits the same characteristics.