Delayed write failure in SMS OSD

Hello

I use SMS 2003 with OSD Feature pack running Windows PE 2005 to deploy my machines. To repartition the disk before the image download I have a pre-install action running diskpart. This works great for all my dell machines except for OptiPlex GX620, Latitude D620, Latitude D420 and OptiPlex 745. When repartitioning, diskpart hangs for 10-15 seconds after the line "Diskpart has successfully cleaned the drive". Then it creates the partition and there are two message boxes appearing with the text delayed write failure. After a bit of testing I realized that all these machines where dual core so I tried with "Multi core support" turned off in the BIOS and now diskpart runs as fast as ever and the messages boxes don't appear. Has anybody had the same issue? The problem is that I can't turn multi core support off as a workaround cause I have a post-install action adjusting sysprep.inf to run on all HALs so I need to know how many cores are in the system.

Regards