Windows xp boot up stops with "did not load driver acpi uniprocessor pc"

That's good.

It could just be one device...  mouse, keyboard or the hub.  Perhaps more fault isolation troubleshooting is in order.  Plug things in/out one at a time to see if you can isolate the culprit - or just the hub alone, does the system not boot if just the hub is plugged in?  Then add just the mouse and see what happens, then just then keyboard, then both, etc.  You'll figure it out.

If it is the hub, the manufacturer may have some ideas on their support page if you contact them with the symptoms or maybe it is still under warranty.

Many thanks for your response.  As it turns out, you may be something of a genius as your advice has enabled me to successfully boot the PC once again.  I unplugged a USB hub from a port on the front of the computer which was supporting both the USB keyboard and mouse.  I then tried the boot again and hey presto it worked.  I've been using that hub without any issues for over 6 months now and I would never have thought that was part of the problem (or indeed the whole problem).  If you don't mind, I'd like to get your view on possible reasons why the USB hub should cause the boot to fail and what I may be able to do to remedy it.  I've answered the questions you've asked below.

You do not describe symptoms consistent with a failing CMOS battery.

It is normal to see that message (and lots like it) in the useless ntbootlog when booting in Safe Mode as seen in this example of a system that boots fine:

Loaded driver WudfPf.sys

Loaded driver Ntfs.sys

Loaded driver NDIS.sys

Loaded driver Mup.sys

Did not load driver ACPI Multiprocessor PC

Did not load driver Audio Codecs

Did not load driver Legacy Audio Drivers

Did not load driver Media Control Devices

.

.

.

Do you even have a multiprocessor system?  (Remember, we don't know much of anything about your system thanks to the MS Answers forum implementation deficiency of not prompting for fundamental system information when a new question is asked).

No, it's a Pentium 4 PC. 3.07GHz

That log is from a Safe Mode boot, right?

No, that is from a normal boot

What do you see (lastly) in a non Safe Mode boot log?

This is the last entry: Loaded driver \SystemRoot\system32\DRIVERS\srv.sys

Also, on closer inspection, there are a lot of other drivers way down the list that get loaded after "ACPI Multiprocessor" - almost all SystemRoot

Loaded driver \SystemRoot\System32\Drivers\Cdfs.SYS

Loaded driver \SystemRoot\system32\DRIVERS\USBSTOR.SYS

Loaded driver \SystemRoot\system32\DRIVERS\usbccgp.sys

Loaded driver ??\C:\WINDOWS\System32\Drivers\sunkfilt.sys

Loaded driver \SystemRoot\system32\DRIVERS\IrBus.sys

Loaded driver \SystemRoot\system32\DRIVERS\hidusb.sys

Loaded driver \SystemRoot\system32\DRIVERS\hidir.sys

Loaded driver \SystemRoot\system32\DRIVERS\ndisuio.sys

Loaded driver \SystemRoot\System32\Drivers\Fastfat.SYS

Loaded driver \SystemRoot\system32\DRIVERS\rdbss.sys

Loaded driver \SystemRoot\system32\DRIVERS\mrxsmb.sys

Loaded driver \SystemRoot\system32\DRIVERS\ipnat.sys

Loaded driver \SystemRoot\system32\DRIVERS\netbt.sys

Loaded driver \SystemRoot\System32\Drivers\AswRdr.SYS

Loaded driver \SystemRoot\System32\drivers\afd.sys

Loaded driver \SystemRoot\system32\DRIVERS\netbios.sys

Loaded driver \SystemRoot\System32\DRIVERS\RDPCDD.sys

Loaded driver \SystemRoot\System32\Drivers\Msfs.SYS

Loaded driver \SystemRoot\System32\Drivers\Npfs.SYS

Loaded driver \SystemRoot\system32\DRIVERS\usbhub.sys

Loaded driver \SystemRoot\system32\DRIVERS\rasacd.sys

Loaded driver \SystemRoot\system32\DRIVERS\ipsec.sys

Loaded driver \SystemRoot\system32\DRIVERS\tcpip.sys

What is your system make and model?

Philips Freevents desktop PC.  Running Windows XP SP3 Media Center Edition. 2GB RAM

What is your definition of a Recovery Disk?

The Windows XP System Restore dvd

If your system will not boot, how did you get the log?

After the boot failed, I shutdown and booted straight into an Ubuntu disk then retrieved the log

If your system used to work properly what do you think changed since the last time it did work properly?

Nothing major that I can think of.

Any hardware changes?

I did install a new 1.5 TB Hitachi hard drive over six months ago, but it has been working perfectly all that time.

I would start using a process of elimination starting with hardware devices.

The next thing that wants to load are the keyboard, USB and mouse drivers so if you have any USB devices attached you may want to unplug all peripherals, reboot and see what happens.

If the keyboard on your system of unspecified make and model is USB then I would use a PS/2 keyboard if you have one - you only need a keyboard to boot and navigate your system so unplug everything else (as a test) and see what happens.

Again, thanks for the help and if you have any further insight into what is the underlying cause of this, I would really appreciate that.

Thanks for the quick reply Andrew.  I've tried your suggestion and taken out the battery, replaced it and gone into the BIOS, but unfortunately, the boot still stops dead after the Windows xp splash screen.  So I'm open to any other suggestions...

At this point,windows hasnt started yet,its in MS-DOS..

With an older pc,if a desktop,a simply recommended try would be to,power-off

pc,remove the MB battery,wait 10 minutes,replace with new battery,start pc.

On pc start,enter the BIOS,reset date/time,adjust for add-in cards,etc,save and

exit BIOS..

Batteries only run for a few years,this controls the BIOS (basic input output)w/o

it,the pc runs in a "loop" on start-up...