I have this issue with different web-hosting, particular upload scripts which can only upload to a folder only if it has 777 permission (which is risky). On the test server (on a different webhost), 755 works well.
On another web-hosting, log files generated by PHP file functions cannot be write to some time, but other files are mysteriously unaffected (for instance, the log files for the entire week is 655, and they work well, but just today's log-file doesn't work unless it is set to 777).
I am more of an application developer than a server backend expert, so these behaviours puzzle me to no end. Why are they happening? What can be done?