Memorex once had a bad reputation for some media, so that is not out of the question. I never followed the issue as I only use Imation CDR media - I have used 2 Fuji CDRWs with no errors and Verbatim CDRWs are always bad for me, tried 3 Verbatims.
Have you upgraded W98 since installing Adaptec software? If yes, there is a good chance the ASPI software layers are now at mismatched revisions. I speak from experience on that matter. To repair ASPI problems, search through Adaptecs downloads for ASPI and ASPI Check utility for more information.
Lastly, I have used dpaehls freeware EASY BURNING software to blank the Fuji CDRWs (
link). The Verbatims which I tried to format were attempted under an older version of EASY BURNING, I am not totally certain that version was bug free at that time.