>That is a relief. That I had not missed anything good, I mean. I have 'always' used PKZIP myself, but mostly I simply RUN it, I don't mind the DOS window flashing for a few seconds.

I'm still using PKZip for that (the last, IMO, freebie command-line version, 2.5). And I call it via late Ed Rauh's API_APPRUN class, so it runs completely hidden, and it waits until finished. No problems ever since I got the parameters right :).