Generic Host Processes is a windows component click here
but it could also be spyware or a virus masquerading as this process i believe.
check in control panel/performance and maintenance/administrative tools/event viewer under the system and application tabs for any errors listed relating to it maybe.click the error to find out if there is a fix available.
what i would do also is check the start up programs in xp: click start/run and type msconfig and click the start up tab.untick everything except your av and firewall and restart the computer.
download,install and update and then run both adaware and spybot click here click here delete anything they find on default settings.they make a back up before deleting so you can always restore anything you remove easily.
disable system restore and update and run your antivirus software and also delete anything if found.
update windows also with any security or critical updates click here
test your firewall click here click proceed and click on the file sharing and common ports tabs to test your firewall.