I have 4550 crossflashed to 4551. For some time now it can't burn dvdrw (+ and -) properly. It doesn't report any errors during of and after burning, but when i try them on different drives (LG, Pioneer) at my friends', they don't recognize the disc. Is this normal behaviour? I've bought the drive in december 2005, but haven't burned that much discs on it - maybe 100.