Invisible network computers

[ulez]

Hello!

I am maintaining a small computer network (less than 20 computers running win xp pro and win 7, one network printer and 3 wi-fi access points) and I am unable to explain some behaviors of some of these computers.

From time to time, some computers are inaccessible from some other computers, i.e. computer A cannot be accessed from computer B but can be accessed from computer C. After I restart computer A, it can be accessed by all computers again.

Windows firewall is off on all the computers and Kaspersky Internet Security is set to 'trusted network' on all the computers.

Any ideas about this? Thanx in advance.

[Wand3r3r]

How are you handling ip addressing? Single dhcp server?

[ulez]

One of wi-fi routers acts as DHCP server i.e. router and other two just as switches i.e. access points.

[Wand3r3r]

if you do a ipconfig /all is netbios over tcp/ip set to enabled?

[ulez]

On the computer which is occasionally invisible by some others, "netbios over tcp/ip" is not listed on ipconfig/all.

[Wand3r3r]

That being the case it does not participate in the browser list.

go to the wins tab and enable netbios over tcp/ip