Here are sampled some very common problems encountered when installing Pydio.
Please check the various points below : 
	. Pydio requires PHP5 at least to work. On some hosting, many php versions are installed, an you may have to explicitely specify that a given folder (and all it's subfolder) has to use PHP5. This is for example the case on the french host OVH.
	. Pydio requires that PHP error level is set to something upper than E_NOTICE : since it was developed for php4 at the beginning, Pydio is not E_NOTICE errors free, thus if your PHP error level display these E_NOTICE errors, many features based on ajax calls will not work.
	. Uploads / Downloads problems : there are a bunch of config that you have to understand in your php.ini : the various variables for memory configuration.