ROX makes my memory card / USB drive read-only!

I have an .XLS file on a memory card, that when i open it via a left mouse click in ROX-Filer, opens in ooffice as read-only. However when I open it from the command line with "ooffice file.xls" it is not read-only.
There is a catch here though. If i open it with ROX-filer FIRST, before opening it command line, it will be read only. However if I open it with command line, and then ROX-Filer it is writable.

ROX never tries to make a filesystem read-only. However, if the kernel driver detects an error in the filesystem then it may remount it read-only to avoid further damage. Check the output of the dmesg command.