It was a Dell Inspiron e1505 with 2GB RAM. Since it's from 2006 and a slow HDD I snagged a bigger SSD 120GB for 30 bucks from Amazon. The office had a spare W7 license so the Dell got its BIOS up to date and then I installed W7. So far so good.
I took the W10 upgrade and it's running great without any driver hunts so I'm good to go.
Boot time is 33 seconds from power on to a google result from Firefox.
As to your issue, Firefox from what I've read isn't supporting that OS anymore so try cleaning off Firefox and all Firefox addons and Firefox folders then install the last version that supported XP but don't install any addons. Do not install Flash support.
I am running Windows XP, SP3 on an older computer. I cannot upgrade without replacing the computer, which is definitely due, but not in the budget. My question is, why am I receiving messages saying that Container.EXE has encountered a problem and has to close (which apparently crashes Firefox)? I find this very annoying. Is there any fix for this? I also get a message every time I boot up the computer that says (simply) "Failed to run service." with an OK button. What isn't being run, or how do I find out, and is it related to the container.exe problems?