Why do we always have to click repair (by 2 users)

What the repair option does is more or less disable and then enable the network connection to refresh the systems settings.

This article explains what exactly it does:

http://www2.lut.fi/atk/palvelut/PCTUKI/W...

? Attempts to renew the DHCP lease, if the connection obtains its IP address through DHCP, using a broadcast message.
? Flushes the Address Resolution Protocol (ARP) cache using the command
arp -d *
? Flushes the NetBIOS cache using the command
nbtstat -R
? Flushes the DNS cache using the command
ipconfig /flushdns
? Reregisters the NetBIOS name and IP address with WINS using the command
nbtstat -RR
? Reregisters the computer name and IP address with DNS using the command
ipconfig /registerdns

So if this is what is being done, lets try to trouble shoot each symptom and see what resolves it.

My first inclination would be to check your DHCP scope on your server, and see if your scope is running out of space. Also check the lease length and see if it is set to a small amoutn of time. Your PCs could be losing their IP addresses and thus need to get new ones all the time.

Are you pinging by IP or name. I would do most of the ping tests by IP as that would remove any of the name resolution issues you may be encountering.

Is the wireless brindge doing any type of mac-address or arp filtering?

Also, can machines in the extension always ping each other constantly? This would help narrow down the problem to see if it is an IP problem on the hosts or a possible network equipment issue.