wrong cmos setting alert

[UNIORYOU]

recently I connected an old cd rom drive via usb to my computer.
I get the wrong cmos setting alert when launching my system.

pressed F2 bypassed the alert .

I noticed media center could handle no more than 2 hard disks but would it
hurt to add another cd rom drive for peripheral?

please advise.

thank you.

simplistic computer specification:
windows media center edition 2005 (all languages)
hard disk (internal) 49 gb (external) 320gb (usb connection)
disk drives (internal) dvd-dlrw pioneer
(external) acer 50x cd rom drive.
memory module: 1ghz
antivirus program: avira antivir personal

another question is why I could not retrieve what has been written for
response when I click the link on hotmail?
It happens all the time I have to look through all the ways to get my post
publicized.