If you delete the cache directory contents... does ez create new files there?
Is this from a "standard" installation or did you change some ini's. There are some ini values, that tell ezPublish, where it should store the "data" (i think, there is "VarDir" and "CacheDir"... check your site.ini.append.* files). It's important, that the settings are the same for your admin and your user site.
Just some quick thoughts, maybe they'll help you. I too had some problems with the cache, but "Clear all Caches" allways helped, though it's not an elegant or efficient way to work.