periodically slow/freezing network

the network is periodically slowing/freezing down in all rooms for some reasons. when a student navigates their network drives and folders suddenly the egg timer appears for about 10 sec and then it goes away and the navigating becomes smooth and fast and then after about 5 minutes or so it happens again. it happens throughout the network. The internet speed is fine, I used http://speedtest.net/ to check, the download speed is 16399 and the upload speed is 7693. it is just the periodic freezes while navigating through the network drives. I checked our cabling it is fine. The only thing I did recently is that I modified the Application Control "default policy" in Sophos Enterprise Consol to stop pupils from playing games and using Ultraserf. I have now disabled that policy but the problem is still there. Any idea guys please help.

Sorry I just realised i posted the thread in a wrong section of the forum but I dont know how to move it to the network section

Maybe you could audit the physicalDisk and the Network interface for a period of time. See if that throws any light on the problem.

Do you have any redirection of start menu/application data etc?

I have seen that cause this type of simptom, if the server starts to slow down, it can take all the clients with it.

Robk

Sophos has lately been the bane of my life resulting in complete lockups... It was bad before and I put it down to a WLAN but I'm no longer convinced it's not related to the Sophos on-access scanner full stop.

Take that with a pinch of salt as I'm hardly giving it a fair shake at bat at the moment.

We had a massive slowdown every so-often in the past, we spent a lot of money on fixing it...

Fibred up every switch, implemented a SAN rather than a PowerVault 745N, added an additional domain controller, SP3 rollout, re-image of multi-PC rooms, massive Group Policy over-haul (removing LMM, restricting user rather than PC), WSUS changes...

I'm guessing that's not what you wanted to hear though :)

McAfee 8.5i Hotfix 5 solved some of the issues, I would say as some tests... remove anti-virus from your file server if it's there, see if that's any better and see if you can disable your AV from scanning network drives (that's what HF5 fixes for McAfee)

Your internet speeds are completeley to irrelevent to browsing network drives (unless of course its a remote network connection VPN over the internet?)

Id suggest checking DNS. Do workstations have the DC set as their primary DNS?

Can you ping the servers by their hostname?

Rush_Tech as you said: "Maybe you could audit the physicalDisk and the Network interface for a period of time. See if that throws any light on the problem."

I think because of the nature of the problem i.e egg timer appears when navigating the network shared drive it seems like a disk problem to me but not sure.
Here is a snapshot of the performance monitor on physical desk Attachment 2919

guys do you see anything wrong with the performance log on my previous reply?