Have two Dell desktop computers with same amount of memory. Both running Windows XP Pro and same version of Firefox. Both have the same Firefox options set up. Both are on the same network connected by LAN. One computer started being incredibly slow to open Google home page. Refreshing Firefox always gets it back to normal but after a day - or two at the most - it goes very slow again. Opening any website takes between 30 and 60 seconds. This delay repeats if the browser is closed. When the browser is open, moving between websites - or opening different websites in a new tab, they load quickly. Have tried with and without private browsing - makes no difference. The only thing I've changed on the computer giving problems is to add a gigabit network card. Disabling it and uninstalling it made no difference. Adobe flash needs updating today but was up to date during this problem. Can't think what else to try.