If you're running on an AMD computer, suggest you contact HP Support before installing SP3. Last I checked, they are still recommending NOT installing SP3, told me to "wait for the official fix"... still haven't heard of one. My notebook is still running on SP2.
installed SP3, got some process eating 50% of CPU all the time. uninstall using MS intruction but still got the same problem. I ended up reinstalling XP SP2 from sratch.
Just a thought... A few months ago I did a fresh install on this Dell machine. When I installed my trading app, the CPU immediately went to 50% and stayed there. SP3 had already been installed. Backtracking, I'd found the Dell video card driver to be the culprit. I uninstalled it and installed the driver from the Nvidia website...problem solved.
Service Pack 3 New features Turns black hole router detection on by default [49] Network Access Protection client Windows Imaging Component [50] Credentials Security Service Provider [51] Descriptive Security options in Group Policy/Local Security Policy user interface An updated version of the Microsoft Kernel Mode Cryptographic Module that is FIPS 140-2 certified [49] Installing without requiring a product key during setup for retail and OEM versions Does SP3 provide better multicore CPU performance? http://windowssecrets.com/2008/09/11/02-Dont-let-XP-Service-Pack-3-hose-your-system
MS even provides instruction "How to remove SP3 from your Automatic Updates " what does that tell you?
Suggestion... Use Acronis and make an image before installing SP3. If it creates a problem, just restore your system to the pre-SP3 with the image. I've installed SP3 on about a dozen machines without issue, however there's a known issue with AMD CPUs from HP... which I've not heard is resolved as of yet.
Might want to check this out.. http://msinfluentials.com/blogs/jes...ed-computer-boot-after-installing-xp-sp3.aspx