Looking up Info-ZIP shows a user-group that have created 'free, portable, high-quality versions of the Zip and UnZip compressor-archiver utilities that are compatible with the DOS-based PKZIP'.
Apparently their versions have been used in quite a number of places.
Some of the more interesting ones (well, historically speaking)
include the use of UnZip code in the unzip.dll distributed with IBM's
OS/2 Warp BonusPak and WebExplorer, as part of the reinstallation code
for the IBM Aptivas preloaded with OS/2 Warp, and as part of IBM's
Infoprint product. Sun used Info-ZIP's self-extractor to distribute
the NT version of their HotJava browser, Novell uses UnZip for NetWare
6 installation, and SAP includes it in Business One. Various Windows
products such as WinZip and the DynaZIP DLLs incorporate Info-ZIP
code, too. And let us not forget Pretty Good Privacy (PGP), an
excellent encryption program that uses Info-ZIP code as a first step
in encrypting files. Info-ZIP's primary compression engine has also
been spun off into the free zlib compression library, used in
Netscape/Mozilla/Firefox, the Linux kernel, Windows, Java, virtually
all PNG-supporting software, and countless other products.
Maybe something in that list points to software you may have installed that included the
zip.exe in your windows folder.