16x CRW2100EZ only burns at 8x

This is getting annoying - even though everything in My Computer, The CDRW drive, the software is set to burn at 16x or MAX, it only burns at 8x. If I do a simulated burn, it will hit 16x, but then the actual burn is only 8x. It does the same thing in EZ CD Creator 5.x, Alcohol 120%, CDRWin, CloneCD. The OS is WinXP Pro, Yamaha 2100EZ burner, and Vertbatim, Memorex, Imation, and Radio Shack media. It doesn't matter which brands are used, it always maxes out at 8x. It must be a WindowsXP problem but I can't find any fixes that work.