I know this thread is old, but for the benefit of anyone else having this problem:
1. Deleting the lines containing QL2300.SYS in the MassStorage.inf file doesn't work.
2. What worked for me is extracting the Storport.sys file from the KB939315.exe and using this to replace the existing storport.sys in the \BartPE\I386\System32\Drivers folder. Then building a fresh ISO using UBCD4Win (press F5 to just build a new ISO from existing output files).
Extracting the storport.sys is a little tricky (but I hate NLite), just run the KB exe file on a machine that is not running 2003 server (I used an XP machine), when the error message appears don't click OK. The exe will have created a folder on the root of the drive you are running it from (which it deletes immediately after you click ok).
Hope this helps somebody.
I hit a seperate problem after this after this, with the i2omp.sys file :-(