Can u verify the following key in the registry on the server you are using for PXE.
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WDSServer\Providers\WDSTFTP]
ReadFilter=
\boot\*
\tmp\*
boot\*
tmp\*
\SMSBoot\*
\SMSTemp\*
\SMSImages\*
The access violation could also mean that u simply dont have access to the needed files.