sims 2 pets 'please ensure cd 2 is inserted' please help!

hey.... yes another question about 'insert cd' ....
i have had pets since it was released n it worked fine... then i got a new computer n i just installed it since i have a real strong and sudden urge to play (no problem with installation!) but when i tried to load it..... yep you guessed it! 'please ensure pets cd 2 is inserted"
i checked the sims 2 site trouble shooting and pretty much everything seemed fine.... i tried to do the start run thing however ... and when i typed in my cd drive it said :"The device is not ready"
what do i do!

P.S i installed the updater package thingy for the sims 2 pets...
P.P.S: im not sure how to do my specs for you ... i keep forgetting how to find it .... but it is a brand new mail order Dell 1 gig ram and 250 HD .... anything else you will have to aid me as to where/how to find the specs ... sorry im so useless