If it is the Windows firewall that is turned off One Care disables it since it provides firewall protection. If it is the One care firewall turning off please post back or contact support - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
If you don't have One Care installed you can get help with the Windows firewall here - http://www.microsoft.com/windowsxp/expertzone/newsgroups/reader.mspx?dg=microsoft.public.windowsxp.help_and_support&lang=en&cr=US
Hi KaitlinM,
I agree with Jim, you may want to contact support if this is a OneCare firewall issue. You may also want to try the new OneCareFirewallRepair tool, which is available here: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=7ee728a2-3c67-4a12-8d7e-954e86233206
Regards,
-John