Problems with DVD-RW

1,5 years ago i´ve bought the BENQ DW1640 which burned DVD-+RW completly satisfying.
Recently i got in trouble with the BENQ drive not being able to overwrite onces burned rewriteables. it simply told me that the DVD-ROM can not be erased, somehow it changed the bitsetting, so i used BENQ Suite 2.1, NERO-DVD Speed and Bitsetter to change the DVD-ROM back to the original DVD-RW type, which simply not worked (the options is grayed out).
So i thought the burner is defective and its RMA time, 1 week ago i got a refurbished BENQ DW1640 and tried it again with no result.
Today i bought the Samsung SH-203B and wanted to erase my DVD-RW media, which is simply impossible because also this drive recognized the DVD-RW´s as DVD-ROMs and changing the bitsetting is also impossible…
what now ?

Thanks

P.S. I also tried Verbatim DVD-RW, SONY DVD+RW, Platinum DVD+RW

Gigabyte P35-DS4
INTEL ICH9R in AHCI Mode
Drives connected to Intel Controller

Now i´ve burned a cd-rw, which is now being recognized as CD-ROM,
i also can not erase ist anymore
P.S. this was a new not used CD

doesn´t even work if i uninstall all virtuall drives, and connect the dvd-drive to my second controller (Jmicron)

problem solved, its a compatibility issue with the damoen tools scsi driver
if i disable it everything works fine

Thanks for presenting the solution, so others don’t have to RMA their drives for a software incompatibility.