Burner won't burn CD's

I have a dell 4700 w/ a NEC 1100 DVD burner. The problem i'm having is I can't burn any CD's. I can burn DVD's just fine and I used to be able to burn CDs. It seems that no matter what program i use it won't burn. I have tried to use nero, roxio, quick burn, and win xp's burn utillity. I am using Optimum CDRs and Sony CDRs but neither will burn although they used to at one point in time. The DVDs i use are Philips DVD+R's and they work fine. I know the CDs are good because they will burn in my gateway PC w/ a sony burner and they work fine in my dell inspiron 5100. Any ideas?