Lexar Professional SDHC 133x Speed write-protected

I have recently bought a Canon T5i and formatted my Lexar Pro SDHC 133x Speed on the camera, which was fine.

I can transfer images/videos from my SDHC to my computer but I can't modify images on the card nor delete images on the card from my computer.

I can still take pictures with the card and delete images on camera.

What bother me is the inability to delete images on SDHC from my computer. And that I can no longer format my card through my computer. I kept getting "write-protected" error massage. Both on lock and unlock position.

Suggestion? Thanks

(Windows vista)