Our small business network has been having reproducible but unexplained connectivity problems lately. Router is Linksys WRT54G (DHCP), machines on network run several flavors of XP, a couple Vista, and a handful Win7. A Macbook also connects from time to time. All, with the exception of the Mac are in the same workgroup. We are not using homegroup. I have disabled IPv6 on all Win7 and Vista machines by unchecking it in adapter properties. I have made no registry changes in this regard although I have read about some that may be necessary. Everything has been running smoothly until recently when an new Win7 Pro x64 machine was added. There was already a similar machine on the network, but the new one replaced our Quickbooks (2008 Pro) server which had been XP. Then things started to happen. Other machines would lose internet. Often they would be able to see local shares and interact with them but no internet. Sometimes neither. Tried reboots, ipconfig /renew, router power cycling, manually resetting winsock settings and combinations of the above.
eventually, the affected machine/s would reconnect. Winsock changes/restart/router cycle seemed to be most effective. What is odd, is that not all machines would be affected at the same time. One might go down. Or two or three, but never all and never the Quckbooks server. In other words, the router and the new machine were always happy together. Only one other machine accesses the Quickbooks data, but is on all the time. It loses connectivity.
This is beginning to sound like a logic puzzle, sorry. Conicidentally, another local business with a similar but smaller network, also running Quickbooks (2010 Pro) on a win7 machine is experiencing identical problems. They are also using a Linksys router (wired only). IPv6 is configured but not needed. Both offices receive internet through the same local Wifi provider.
Often, they will lose internet on their server but retain local share access including QB access.
Hope you can offer some insight - I am out of ideas.