How do I prefent Buffer Under Run Errors?

[wisard]

Help me plz.
my system:
PII 300MHz, 64 MB RAM, Seagate HD 6.5 GB, Maxtor 20.0 GB, AOpen CD-reader (32x) and a HP9310i cd-rewriter (all of these devices are (E-)IDE). I always have one partition empty for burning, so it's not the fragmentation.
The only program running is the burning program e.g. nero, clonecd, cdrwin etc.
When I try to burn at 8x or higher in my case 10x (max) I always get buffer under run errors
But at 4x the burning process went perfectly.
Ther was a time when I just bought the HP9310i and I could burn at 10x but unfortunately not all the media were suited for 10x. So I had to switch to 8x. This worked fine untill now! Now all I get are Buffer Under Run Errors at 8x or 10x
how do i prefent this?
plz help.

greetz wisard.