I'm confused (backup of network share vs/& archive attribute)

I connect to an XP share from a windows 7 box. Said share/folder is backed up locally simply by winzip (only backup if archive attribute is set and unset). However, every(?) time the connection is made all files have the archive attribute set back to ready which kind of stuffs my regime. At this stage I've no idea what's going on but am trying to rule out True Image Home 2010 installed on the W7 box. From what I've read TI isn't interested in that attribute but is there some peculiar about how persistent shares are treated?