HEY EVERYONE i got a xperia x10 from wirefly couple weeks ago.It is a brand new phone everything goes pretty well. but one problem is i cant install any programs that i downloaded from other sites.The security is set to block the installation of applications not from Android Market. i did the research online and tried to clink setting--->application--->there are only two choices on there 1.manage application 2.development. I could not find the third choice,which it suppose to be "UNKNOWN SOURCE". IS THERE ANY WAY TO SOLVE THIS PROBLEM??PLEASE HELP!!THANX!