I have tried about 8 versions of unofficial update Rollup, some very old just to see if any would work. All produce the same result. Computer wont boot. This is not a fresh install, I have been running windows 2000 since I purchased it new on this computer. It is an older computer, the mother board is a Gigabyte GA - 8S66IFXM - 775, 1024 mb memory DDR 200 Mhz. The other software before UUR is unofficial service pack 5.1 & then update rollup 2, both of which load on fine. At one stage, I omitted to load update rollup 2 to see if it would make any difference but as soon as uurollup is installed, computer wont boot and message winnt/system32/config/system missing or corrupt appears.
Everytime I get to this stage, I use Acronis to reinstall the disk image before I loaded uurollup.
As per ironman14 above, when this happens, it wont boot into safe mode & I believe any repair using the windows cd will undo the state I am trying to get the computer into, so I can run a higher version of firefox, rather than version 12 which I currently have to run.
I did at one stage install an already updated ISO file of windows 2000 & it ran firefox's latest version, I did this just to see if it would actually work on this computer but this meant I would have to find all the drivers, reload all programs etc, this was not really an option (being a huge job) when I should be able to update the existing installation & enjoy.
Thanks for the interest but still looking for an answer.