Hi,
I'm sorry the quality of this code isn't good, I didn't have much time at work to drop out the ICSharpCode library and replace it wth yours so I just did a quick fix that remained API compatible with your existing code ( i.e. ZipFile & ZipEntry).
 
If I get a chance this w/e I'll abstract it properly into a ZipOutputStream class or something, and provide a ZipFile constructor that works with Readable Streams perhaps, but I'm snowed under so I can't guarantee it.
 
I had a problem with extracting the created zip-files in Linux under Java (I'm specifically using this code to package 'BPR' files up for passing to Active Endpoint's BPEL orchestration engine which being an Interop kinda chap I'm sure you'll appreciate my pain!), so the paths being passed as ZipEntry's have a .Replace("\", "/") being applied to them. Everything seems ok with this additional change, so I'm mainly letting you know in case you don't spot the change [also I notice that you check for forward slashes to determine whether an entry is a directory, so the compression should be more compatible with that code now].
 
I did have 'diff' file for you, but I couldn't seem to come up with a version that I could successfully patch the original code with , strange.
 
Please find attached my modified code, and associated buidl artifacts
 
 
Cheers