Vista - Can not write to USB hard drive and disk drive due to "read only"

I have just bought a new computer with home premium vista 64 bit.

It has all been working well until I tried to do a backup using acronius true image 11. That was when I realised that I can not write to any external devise via USB. Both my hard drives and a USB memory stick come up with the error "device is write protected, remove the write protection or use another device". All these devices work fine on my other computers which run vista 32bit and windows XP.

I have tried using diskpart which didn't work. I then tried going into the properties of the disk, then going into the security tab, hitting edit and clicking on allow write, but says "an error occured while applying security information. E: The media is write protected" I have searched through

I have an MSI P7N diamond motherboard (nForce 780i chipset) with 4gb of ram. 500gb WD HD. GTX 260 graphics card and Intel dual core E8400 CPU. I ahave downloaded and install all the latest vista updates and the drivers for my motherboard.

Any advice would be greatly appreciated.

Thanks for taking the time to read this.

James.