What happened to my Memorex CD-RW

just bought a Memorex 48x24x48 fews day ago, but it is kinda weird that even it is before or after I flashed it to 52x24x52, the average speed of writing is 10x. it writes 48x only at the first four or five seconds, and then it slows down. It takes over 6 minutes to write a 670MB image file. Anyone knows what’s goin’ on?

What are your system specs, and what type of disc are you using?

using Windows XP HE, set it as secondary slave drive. I’ve tried many kinds of CD-Rs such as Optimum, Sony, Maxell, and other cheap ones. They didn’t make much difference.