HomeGroup, One down, rest still working

Computer one: laptop HP w/ AMD Turion 11 Ultra. Computer two: AMD Phenom 11 X4 955 both running Windows 7, 64 bit, Computer three: Intel E8400 , Computer four: Intel E7400, Computer five: EEEBox Atom N270, all running Windows 7, 32 bit. All part of a home group, home network. Computers one and five are wireless, computers two, three and four are hardwired. All through the same router. All was working fine. Have 32 bit printer connected to computer three which computers four and five could print to thru the network. Have 64 bit printer connected to printer two that all computers can print to thru the network. File sharing was working through all computers to all computers. Was running mulit-player game play through computers one, two and three as these were computers that have the games on them. Suddenly computer one was not showing itself on the network. Thru it could see the other computers on the network but could not open up their shared folders. The other computers can still see all the computers on the network and open up all the shared folders, even computer two that can't even see itself. LAN play between all the computers still works, even with computer two. What has happened to make computer two not see itself or able to open up the other computers it still sees on the network?

Reply 1 : HomeGroup, One down, rest still working

Even with 7, names and passwords still cause folk problems like this.

Reply 2 : HomeGroup, One down, rest still working

We did not set it up to use passwords and nothing was changed. We all have password protected sharing turned off.

Reply 3 : HomeGroup, One down, rest still working

Antivirus and firewall updates tend to break this. It's why I added a note about the firewall.