>>>>>>I have not tried it, but what happens when a tool such as WinZip (32 bit version) tries to create a zip greater than 2G? I would suspect that the problem is with 32-bit and the ability to access files greater than 2G in size (2**32). If this is the case then you will have to use a shell command and a 64-bit version of a zip compressor to create the zip archive file that is greater than 2G. You cannot call any active-x component that is 32-bit to create files greater than 2G.
>>>>>
>>>>>I wonder if that is true? I could zip a file larger than 2.5 GB, so the limit is not at 2G, which means it has nothing to do with 32-bit.
>>>>>I will try the shell command, but it will be much more work to integrate, so I was hoping for some other third party tool that I could use.
>>>>
>>>>Another question - what is the size of the resulting zip file when you zip a 2.5GB file? That may well be less than 2GB. But, maybe when you're zipping a 3GB file, the result wants to be greater than 2GB.
>>>>
>>>>Exactly how large is the "corrupt" zip file?
>>>
>>>The resulting zip files are well below 1 GB, mostly around 300 - 500 MB
>>
>>Have you tested on multiple machines?
>>
>>Somewhat related, you might want to test with AV real-time scanning disabled.
>
>Yes, it's the same on all machines, that's how we found it out because it happened at a client.
>I have usually AV disabled on my development machine, so that has nothing to do with it.

Option 1 would be to ask Craig to look at it, but I haven't seen anything from him in years, dunno if he's still active in VFP. His last blog entry on his site was May, 2010.

For my own interest I briefly looked into alternatives:

COM DLLs:

- 7Zip has a "COM DLL" but they say it's not a standard one so it's unlikely to work with VFP (?) http://www.7-zip.org/faq.html#developer_faq

- Info-Zip has DLLs that supposedly can be used from VB: http://www.info-zip.org/FAQ.html#VB but that doesn't guarantee VFP compatibility

ActiveXs: didn't immediately see any that were free or FOSS:

- Chilkat: http://www.chilkatsoft.com/zip-activex.asp
- Bricolsoft (expensive): http://www.bricolsoft.com/zip-activex-component.html

Command-line:

- 7Zip is probably a good choice