plextools DAE is still a better ripper than anything by Creative. you can enable CD/DVD SpeedRead on the 708 (or use the 3 sec eject button trick).
do any of the CDs in question have some sort of copy protection? try ripping with a different program. if that works, it's the Creative crap at fault.
i've got FW 1.09 on my 708UF and it's worked without a hitch so far. you could try flashing up OR down to see if that helps as well.