My Eee PC 900 running Base 3.0 seems to claimed exclusivity of my SD Card.

This problem appears to be as a result of an SD card being in a weird state. The SD card I that usually resides in my eeepc eeebuntu 3.0) behaves as expected in this machine, or in my phone (SPV M600 running WM5) . When it is in my main PC (running Ubuntu 9.04 or XP in VirtualBox) it claims to be read only and won't let me write to it, delete from it, format it, or delete the partition. When this SD card is in my Navman S30 GPS or my phone they refuse to connect to anything via USB. Eject the SD card and the device appears, weird!

Does anyone know how I can get my Eee PC to let go of my SD card and let others use it?