I have Windows XP SP3 on a Dell Dimension 4550.
It's possible you installed SP3 incorrectly (Microsoft doesn't make it
easy!).
Here's the first thing I would do: Uninstall SP3 (Control Panel | Add or
Remove Programs). Then reboot and perform a System Restore to the time
before you installed SP3:
Start | All Programs | Accessories | System Tools | System Restore
Hopefully that will fix your problem. If so, please let us know and
someone will instruct you on the best way to install SP3.
For reference:
(For those who have PCs with AMD processors and OEM images, especially
HPs:)
"Does your AMD-based computer boot after installing XP SP3?"
(or http://tinyurl.com/6zs52d )
"Windows XP SP3 - Read all prerequisites for a successful installation"
(or http://tinyurl.com/6nf4k4 )
"Steps to take before you install Windows XP Service Pack 3"
http://support.microsoft.com/kb/950717
"Microsoft Windows XP Service Pack 3 (All Languages)" (Free Microsoft
support for SP3-related issues)
http://support.microsoft.com/oas/default.aspx?ln=en-us&prid=11273&gprid=522131
(or http://tinyurl.com/6cw2xk )
MS's news server is acting flaky once more. If you haven't seen my
response already, Felicia, here it is again (I wonder if the Tiny URL
links are setting off spam filtering...):
http://groups.google.com/group/microsoft.public.windowsxp.general/msg/f28c61614b3b006d
Contact the supplier of "something." They may want you to have the version 3
MS installer.