Finally, the reply regarding the one-byte .cat file:

If it is an error it will be corrected, the driver developers have been forwarded this feedback as well.  If it is the way it is supposed to be, it will remain as is.

Just for the archive:

mr_smartepants wrote:

Complain to AMD/ATI for not properly signing their drivers.

My complain at the AMD Global Customer Care resulted into:

If you wish to use WHQL certified drivers for your legacy product, try the Catalyst 9.3 drivers.
Any driver version past this will not be WHQL certified and this will not change.  Drivers past 9.3 for the legacy products are hotfix releases and do not get passed by Microsoft certification, without certification from MS they do not get to be designated as WHQL certified and the code cannot be changed without Microsoft's approval/certification.

This reply does not answer my question about the invalid cat file, though.

mr_smartepants wrote:

Yes, and if you unpack the official AMD/ATI drivers from here you'll see the same thing.
Complain to AMD/ATI for not properly signing their drivers.

Oh, I see, I will complain.

May I suggest to remove any invalid certificates from the DriverPacks, or rename them to XYZ.cat_invalid or something like that? I removed the invalid catalogue file and DPInst could at least install the driver with help of the driver signer warner disabler tool and the Finisher did installed the CCC eventually. The invalid file caused DPInst to log an error, but ignore the driver otherwise.

Thanks mr_smartepants,

ska

The mentioned file is not a valid certificate, because of this the driver is rejected, I guess, and the built-in driver is used. I have disabled Driver Signing in WinXP/SP3 via dialogue box.

[2011/11/03 11:05:18 552.1298 Driver Install]
#-019 Searching for hardware ID(s): pci\ven_1002&dev_4151&subsys_7c37174b&rev_00,pci\ven_1002&dev_4151&subsys_7c37174b,pci\ven_1002&dev_4151&cc_030000,pci\ven_1002&dev_4151&cc_0300
#-018 Searching for compatible ID(s): pci\ven_1002&dev_4151&rev_00,pci\ven_1002&dev_4151,pci\ven_1002&cc_030000,pci\ven_1002&cc_0300,pci\ven_1002,pci\cc_030000,pci\cc_0300
#-199 Executing "C:\WINXP\system32\setup.exe" with command line: setup.exe -newsetup -mini
#I022 Found "PCI\VEN_1002&DEV_4151" in c:\d\g\a\cx_95952.inf; Device: "RADEON 9600 SERIES"; Driver: "RADEON 9600 SERIES"; Provider: "ATI Technologies Inc."; Mfg: "ATI Technologies Inc."; Section name: "ati2mtag_RV350".
#I087 Driver node not trusted, rank changed from 0x00002001 to 0x0000a001.
#I023 Actual install section: [ati2mtag_RV350]. Rank: 0x0000a001. Effective driver date: 02/10/2010.
#I022 Found "PCI\VEN_1002&DEV_4151" in C:\WINXP\Inf\atiixpag.inf; Device: "RADEON 9600 SE Family (Microsoft Corporation)"; Driver: "RADEON 9600 SE Family (Microsoft Corporation)"; Provider: "ATI Technologies Inc."; Mfg: "ATI Technologies Inc."; Section name: "ati2mtag_RV350".
#I023 Actual install section: [ati2mtag_RV350]. Rank: 0x00002001. Effective driver date: 03/23/2004.
#-166 Device install function: DIF_SELECTBESTCOMPATDRV.
#I063 Selected driver installs from section [ati2mtag_RV350] in "c:\winxp\inf\atiixpag.inf".
#I320 Class GUID of device remains: {4D36E968-E325-11CE-BFC1-08002BE10318}.
#I060 Set selected driver.
#I058 Selected best compatible driver.
#-124 Doing copy-only install of "PCI\VEN_1002&DEV_4151&SUBSYS_7C37174B&REV_00\4&38B71F77&0&0008".
#-166 Device install function: DIF_REGISTER_COINSTALLERS.
#I056 Coinstallers registered.
#-166 Device install function: DIF_INSTALLINTERFACES.
#-011 Installing section [ati2mtag_RV350.Interfaces] from "c:\winxp\inf\atiixpag.inf".
#I054 Interfaces installed.
#-166 Device install function: DIF_INSTALLDEVICE.
#I123 Doing full install of "PCI\VEN_1002&DEV_4151&SUBSYS_7C37174B&REV_00\4&38B71F77&0&0008".
#I121 Device install of "PCI\VEN_1002&DEV_4151&SUBSYS_7C37174B&REV_00\4&38B71F77&0&0008" finished successfully.
[2011/11/03 11:05:23 552.1305 Driver Install]

Regards, ska