MelFish you are correct, rights management in Windows can be tricky, and this is not only about “read-only” attribute, there are also per-user access permissions. Plus, it may also depends on the file system type, and on top of that, there could be another layer of permission control imposed by network protocol, if this is shared folder.
I don’t think we are in the position to provide you complete detailed step by step instruction on how to deal with this issue, since, as I said, this is complicated topic with lots of “it-then”. Sure there are tons of guides on that in the internet, but to be honest the easiest way would be to ask help from someone who can actually take a look at your system and see what is whong.