Version:           4.00.83 (KDE 4.0.83 (KDE 4.1 Beta2) (using 4.00.83 (KDE 4.0.83 (KDE 4.1 Beta2), Kubuntu packages)
Compiler:          gcc
OS:                Linux (i686) release 2.6.24-19-generic

Double click on a zip file

now in the address you are inside a zip protocol
zip://path/to/zipfile

now press the 'Up' button (not the 'Back button', which is foolproof to this bug) .. 

the result is:
zip://path/to/

Expected is: /path/to (without the zip protocol prefix) .. 

now trying to copy a file or move or do any operation in this folder will yield all disabled because konqeuror thinks that he is still inside a zip file.

Good luck.