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I have a domain with about 300 Windows 7 and XP machines, with the domain controllers running Server 2003.

Sometimes, I lose the ability to communicate/authenticate with some of the machines until I reboot my computer. This also happens from other computers and regardless of user account and operating system.

In other words, say I'm on ComputerA, and I can't connect to ComputerX. I can go to ComputerB and connect to ComputerX, but ComputerB may not be able to connect to ComputerY. If you reboot ComputerA, then it will be able to connect to ComputerX again.

Here are some messages from various utilities:

  • sc: [SC] OpenSCManager FAILED 1722: The RPC server is unavailable.
  • mmc (compmgmt.msc): Computer (computer name) cannot be managed. The network path was not found.
  • explorer (\\computer): Windows cannot access \\(computer name).
  • ping: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss) / Average = 1ms


  • netdom verify: The network path was not found. The command failed to complete successfully. (note that this succeeds on the other computers on the network)
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Can you post the results to netdiag – JJ01 Jun 25 '10 at 2:33

The network works, and you're reporting this as happening on multiple computers. I'd say that you need to look at:

  • DNS: Try doing nslookups on the DCs when you run into a failure. Try querying the domain name, and see if you're getting back a valid list of DCs.
  • Apps that you run on the PCs that may be too smart for their own good. Especially firewalls, av, etc.
  • Network firewall rules. Are you trying to block ports > 1024 between the PCs and DCs? Windows doesn't like port range restrictions.
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Run DCDiag and check for any errors. This article can help you look for errors Dcdiag Examples

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I got " Starting test: Services Invalid service type: RpcSs on (server), current value WIN32_OWN_PROCESS, expected value WIN32_SHARE_PROCESS ......................... (server) failed test Services." – Excel Kobayashi Mar 18 '10 at 18:05
Running the server 2003 version of DCDiag, everything passes – Excel Kobayashi Mar 18 '10 at 19:19
What kind of events do you see in System event log? – Vivek Kumbhar Mar 18 '10 at 19:40
No relevant events in the log – Excel Kobayashi Mar 18 '10 at 20:38

I've seen this (years ago) with flaky switch ARP caches. What make\model switch are these computers connected to.


Hmmm... on second thought, a flaky ARP cache on the switch wouldn't explain why ping works...

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other than accessing other computers on the network, do you have the same problem with accessing Servers or Internet?

ARP cache as Joeqwerty makes sense, but, so does a bad networking device like a switch.

Even incorrect DNS settings will cause this.


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There isn't a network problem. Internet, and other network traffic is fine. Ping still works, the computers can communicate, but cannot authenticate. – Excel Kobayashi Mar 22 '10 at 3:50
OK, another question. How many Servers do you have, how many are authentication Servers, and what are the specs of that or those servers. I'm wondering with 300 workstations that maybe you are reaching limits of your servers. Also, how many switches are in your network, is the network still inside of the 432 rule? – Tom Mar 23 '10 at 1:43
We have 3 domain controllers, and about 10 other servers. We don't have any control over the network, but I can tell you it's not very good. Is there a way to tell for sure if the network/server is the problem? – Excel Kobayashi Mar 24 '10 at 23:01
3 Domain controllers should be plenty for 300 workstations and 10 other servers. I'm still curious about the switches and whether your network is following the 4-3-2 rule. Granted that's older technology but their are alot of variables and I dont know enough about your network or if cabling as well as switches are up to standards or are they older and slower, which would cause the problems you are having. I'm sorry to be so vauge, I would strongly suggest your supervisors request an audit of your network from an outside source. HTH – Tom Mar 25 '10 at 20:36

I had the same issues with a few XP machines. I tried all sort of settings for months until one day I changed all the switches (4) from 100MB to GBs and run Windows updates and the problem was resolved.

Check Windows Event logs. I had 2 errors I couldn't track down. I have to check my docs and will post them here...if I could find them.

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Along the lines of duffbeer's suggestions of looking at the DNS and firewalls/AV on the client computers, you may also want to look at any intrusion detection or network management software that you have running.

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