CD-R problems in W2K

I have a hard time with cdr:s in w2k. Have two Mitsumi burners, 2801 & 4801 that simply refuses to behave normally. Tried both on 2:nd IDE. Then as slaves on 1:st. Sometimes they work, sometimes not. On some rare occations I have even been able to write to them. In device manager they are both recognized and said to be working with no problems. But not so in the real world. Anybody got any suggestions?