In order to fix it there are 2 ways.
One is by adding the sw_flash_ver1eng plugin and making changes to XPE.inf or make small fix in XPE.inf only. You can also make it in XPE-custom (I did not tried it).
In XPE.inf in the "Flash support" section change the swflash.ocx to flash.ocx in the following entries:
CODE
0x2,"Classes\CLSID\{1171A62F-05D2-11D1-83FC-00A0C9089C5A}\InprocServer32",,"%SystemRoot%\System32\swflash.ocx"
0x2,"Classes\CLSID\{D27CDB6E-AE6D-11cf-96B8-444553540000}\InprocServer32",,"%SystemRoot%\System32\swflash.ocx"
0x2,"Classes\CLSID\{D27CDB6E-AE6D-11cf-96B8-444553540000}\ToolboxBitmap32",,"%SystemRoot%\System32\swflash.ocx, 1"
0x2,"Classes\CLSID\{D27CDB70-AE6D-11cf-96B8-444553540000}\InprocServer32",,"%SystemRoot%\System32\swflash.ocx"
0x2,"Classes\CLSID\{D27CDB70-AE6D-11cf-96B8-444553540000}\ToolboxBitmap32",,"%SystemRoot%\System32\swflash.ocx, 1"
0x2,"Classes\TypeLib\{D27CDB6B-AE6D-11CF-96B8-444553540000}\1.0\0\win32",,"%SystemRoot%\System32\swflash.ocx"
0x2,"Classes\CLSID\{D27CDB6E-AE6D-11cf-96B8-444553540000}\InprocServer32",,"%SystemRoot%\System32\swflash.ocx"
0x2,"Classes\CLSID\{D27CDB6E-AE6D-11cf-96B8-444553540000}\ToolboxBitmap32",,"%SystemRoot%\System32\swflash.ocx, 1"
0x2,"Classes\CLSID\{D27CDB70-AE6D-11cf-96B8-444553540000}\InprocServer32",,"%SystemRoot%\System32\swflash.ocx"
0x2,"Classes\CLSID\{D27CDB70-AE6D-11cf-96B8-444553540000}\ToolboxBitmap32",,"%SystemRoot%\System32\swflash.ocx, 1"
0x2,"Classes\TypeLib\{D27CDB6B-AE6D-11CF-96B8-444553540000}\1.0\0\win32",,"%SystemRoot%\System32\swflash.ocx"
Copy the flash.ocx and the swflash.inf from your PC to files directory under XPE and add these 2 lines to XPE.inf or XPE-custom.inf
CODE
files\flash.exe=2,,1
files\swflash.inf=20,,1
files\swflash.inf=20,,1