Hi,
Try to update the DOS driver in the PC-DOS boot package.
As you are using 11.5.1 why don't you try WinPE, finding the DOS drivers for the latest machines has become a tough task as the manufacturers don't release DOS drivers for the newer machines.
Instructions on creating a WinPE boot disk is given below,
http://service1.symantec.com/support/on-technology.nsf/854fa02b4f5013678825731a007d06af/7ae75ec20820a4b68825744400672493?OpenDocument
Thanks,
Prasanna
_________________________________________________________________________________________________________
If you feel your issue has been addressed to, please use the "Mark as Solution" link for the relevant thread.