CD/DVD-RW burns CD's fine but wont burn DVD's

[friend2u]

This is not a hardware problem because I had a tech out and he put a new drive in with the same result. The drive reads DVD's ok but syas that brand new DVD's are not writable. When I check the properties of the DVD it shows full, no free space . I have tried both plus and minus all brand new with no success. The tech recommended a system restore but I will lose some apps which I no longer have the disks for. Interesting thing is I bought an external drive today and although it show as a drive in My COmputer when I click properties it shows FULL just like the DVD's. Is something compromising drives or is this beyond that??