That ain't good[xx(]
None of the BenQ firmware upgrades for 4824P work huh? Not a good sign.
I noticed the same thing happening when using mtkflash from dos to backup my firmware. Don't give up on it yet, try running it again, go grab a frosty beverage and enjoy it while waiting a few minutes, mine took between 2 and 6 minutes to backup, I don't remember exactly. I'm not sure, but it may be reading the memory blocks or addresses individually, so it will go from 0 to 100% several times before its done and its slow.
Not sure about CD Speed issue, might be your media, try using different media or certified 48X or whatever speed you want to test for.
I'll send you the files I have, sounds like the only reliable way that you are communicating with you drive is through mtkflash, you might want to try flashing it from DOS just like you are backing it up.
For instructions: http://digi.rpc1.org/A%20Quick%20HowTo.htm
Be carful before proceeding, and Good Luck!