Client is Office 2007 on Vista, saving to ‘Document’s which is redirected folder on a Server 2003 R2 file share. Whenever saving files you get “access is denied” and it creates a 0KB file, but you can copy the file there in explorer no problem. As a side note, offline files and folders is also enabled.

It’s related to SMB2, which is Vista + Server 2008 tricks. See KB 296264 about ensure that opportunistic locks are enabled in the registery on the server.