SD-Card readonly

Hi, can anybody out there help? Is there any brute-force-way to remove
write-protection from a SD-Card connected via USB as /media/usbdisk? I've
tried to change the settings as root, tried to re-format that ***card-
nothing worked. The read-only-status was somehow, without my intention, set
to the SD-Card when I copied some picture-files on it from my machine
running under SuSE 10.0 with a cheap chinese cardreader. Maybe this chinese
rubbish is to blame, because I've copied files to that SD-Card before with
a different card-reader, and everything worked fine....

Regards
--
Rüdiger
.