Verbatim CD-RW Highspeed not working in Pioneer 106 OEM

I have Teac DV-W50D (Pioneer 106 OEM) and after buying i tried to burn something into CD-RW 8-10x Verbatim (mitsubishi developer) medium. After several burning tests i checked the medium using CD-SPEED and get terrible results. There were a lot of C2 errors and the medium was sometimes not readable at all. It seems that drive has problems only with this medium (i tried another CD-RW mediums and everything was ok). Does someone tried to use Verbatim highspeed CD-RW medium with Pioneer 106 OEM?

Another problem is using packet writing on CD-RW. It writes data to CD max 4x speed (not 10x) (reading from UDF is faster then writing to it). Does anybody got same problems? And what about DVD-RW packet writing? Does it make same results?

My first opinion to this drive is not so good as i thought. I also tried another DV-W50D drive, and get same results with Verbatim CD-RW. This medium is working everywhere where i tried it to burn. Could it be, that this Pioneer 106 OEM driver, about which i heard only the best (and also that it has best compatibility to many media kinds) is not working good with Verbatim CD-RW?