Zipper contains several bugs which might corrupt the infected files.
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
This is a simple virus which stays resident in memory and infects COM and EXE files when they are accessed. \COMMAND.COM and \DOS\FORMAT.COM are infected on the first execution.
If you run PKZIPFIX against an infected COM or EXE file, it will create a PKFIXED.ZIP, which contains an assembly source file called ZIPPER.ASM.
The virus contains this text, which is never displayed:
Date Created: 2006-01-01 10:53:46.0
Date Last Modified: 2006-01-01 00:00:00.0