This is how i solved my issue running windows vista. All other solutions did not work. The slide thing was not on lock, i could not find storagedevicepolices so yea hope this helps.
1. go to "My computer"
2. right click "SD card" your Sd card
3. select "properties"
4. Click "hardware" tab
5. under "all disk drive" heading there are a few selection, select your SD card among the options
6. click "properties"
7. under the "general" tab, click "change settings"
8. click "policies" tab
9. then click "OPTIMIZE FOR PERFORMANCE" setting
this setting enables write caching in windows to improve disk performance. to disconnect this device from the computer, click the safely remove hardware icon in the taskbar notification area.
10. click ok
Not all cards have a write protect switch.
I had this issue and found that it was multiple cards all of which didn't have the switch, I quickly realized that the issue was my PC not the card since the cards did work in another PC.
Here's how I fixed it:
open Regedit and navigate to
HKEY_LOCAL_MACHINE\SYSTEM\CurrrentControlSet\Control\StroageDevicePolicies
If there is a WriteProtect key (REG_DWORD) then
1 = Write Protect On
0 = Write Protect Off
Set to 0 and try (may have to reboot in some cases)