Nice that we got that sorted, finally. I think you took the code idea from Patrick, btw. I think the reason is a difference in joomla 2 and joomla3. When I check my j2.5, then there is a cache folder in the administrator folder, but no files (except the index.html). But in joomla 3 I see there files. So it seems that they fixed or added the feature of different cache folders per application (FE oder BE). And this lead to trouble, when we try to delete a cache of the FE, while in the BE. I wonder also if it makes sense to controll the options always, even when just use the cache.