There're plenty of commercial and some free ptoducts that allow to create ZIP files fully compatible with ZIP specs. We, for example, are using Dynazip and quite happy with it.
You can try to play with PKZIP trouble shooting options. To get the list of those options, launch PKZIP /? from DOS command prompt and press number corresponded to the "trouble shooting options". We had similar problem with PKZIP 2.50 and using '-~' switch (Disable Network something) cured it.


>I have a very strange problem. We have a routine that zip's ascii files that were created via VFP. Pkzip is run from a batch file and it is run via the RUN command.
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>When the files get zipped the zip file has CRC errors when it is executed from the VFP app. If the batch file is ran alone the zip file is fine. This same routine is used by about 30 other customers with no prolems what so ever.
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>I really need to use pkzip to compress the files because they get transferred to a Symbol PDT3100 device and it has a version of pkunzip on there to uncompress the files.
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>All of this runs in an automated process when necessary.
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>Thanks for any tips on what may be happening.
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>Tommy