Ext3 on HP ZT 3010ea and overhead

[Marco Guidetti <gaedol@gmail.com>]

Hey all, 
not sure this is a laptop problem at all, but since it's happening
only on my laptop i guess it is :)

i installed Debian on my laptop choosing ext3 as fs. When i move large
files on the filesystem, or i download large files via ssh, sometimes
happens that the _whole_ system freezes for a minute, with the hd led
always on.
After a minute led goes off, and i regain control of my system.

Another strange fact: cdrecord says my cd writer can write cds at 24x,
but despite any kind of statement i can do in the command line (like,
say, speed=16) it burns cds at 8x.

if it can be of any help, dma is on, i just checked with hdparm.
and, anyway, dma turned off hasn't changed the facts...

ideas?

TIA, 

marco