weird permission warnings

When I try to upload a small JPG via the file manager, in a directory I created and set to 0777, I always get this error msg:

Failed to copy file to destination directory - upload failed! Possible permission problems - the directory you want to upload to needs to be set to 0777 permissions.

The settings are 0666 + 0777 in the modx configuration. It doesn’t matter if I create a new directory under assets/images via modx or FTP: the above error ALWAYS shows up.
What’s also weird: Inside the directory, it correctly shows: "Directory writable? Yes."

Again: the folder IS set to 0777. I checked and double-checked. So that clearly can’t be the issue here...

Anyone got an idea? This is the first time I see anything like this. It just doesn’t make sense.

MODx 0.9.6.1p2
PHP Version 5.2.1-0.dotdeb.1
Apache/1.3.33

OK, I re-uploaded the mcpuk folder, but the same stuff went on.

I realized the problem is maybe more with CREATING folders:

If I create folders within the file manager, I get those silly warnings when trying to upload a tiny JPG. Although: when I check via FTP, the dir is really set to 0777.

If I create the folders with FTP, everything works at it should.

Now, while this behaviour is acceptable for myself (I’m always using FTP), it would be a nuisance for the client who has to use this tool later on :|

I seem to be having similar problems on a new host.
Will check more tomorrow regarding creating folders via FTP versus via the file manager.

Could this be a "php in safe-mode" issue.