wp-cache error: cache directory () did not exist

Hi there,

Last week our WP-CACHE plugin suddenly stopped working. When we log into wp-admin and check the plugin options, we see this error:

Error: Your cache directory () did not exist and couldn’t be created by the web server.
Check permissions.
Cannot continue… fix previous problems and retry.

I have checked, doublechecked and reset the permissions to 777 on the wp-content and wp-content/cache, disabled, deleted and then re-installed the plugin and the cache directory, and still no luck.

I have been searching for days and haven’t found any reference to this error anywhere… any help would be much appreciated!

Thanks!