sure i will give you some suggestions... and ask some questions.
First the discs youare having trouble reading i assume you did not record them on this computer so i need to know:
1) how were they recorded? using directcd perhaps? if so they will not read until you close them
2) have you tried to record cds with the 48161h? if so are they readable in the drive itself and in other drives?
on the media side your fujis are excellent discs the memorex far less good. i find them to be a very marginal disc on my 7 burners (52246 x 2, 48161 x 2, 48246, 411s, 811s) so i just use them for stuff i am not worried about for perminent storage so that may be your issue.