I don't know but the following quote from Archive::Zip::FAQ might be useful:

You can unzip PKZIP/WinZip/etc/ archives using Archive::Zip (that's what it's for) as long as any compressed members are compressed using Deflate compression.

So, maybe ask the user to check the compression settings.

If you need alternatives, I've yet to come across a zip file that couldn't be unzipped by debian's version of infozip

update: oops didn't read well... it seems strange to me that that wouldn't work. What happens when she tries to unzip a zip file created with winzip 9? Maybe the winzip 10 install is buggy...