Slow exploring UNC Share, then hangs

When I am sitting at a remote machine and type in \\servername\c$ and start delving into the folder directory the explorer window starts getting slower and slower, when I'm about 3 to 4 folders down it pretty much hangs.  It only happens on these remote machines which are on a cisco switch connected via a 100Mbit Fiber, about 300ft.  It seems to only be affecting file exploring, I can use RDP to remotely control the servers with no problems.  I checked and verified that the Full duplex and speed are hard coded correctly on all the ports and devices.  Unfortunatley I don't have equipment to test the fiber.  What I don't understand is why it is only it only seems to affect file browsing through a UNC.
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dlangrConnect With a Mentor Commented:
since OS and hardware at the clients is not making a difference, the client machines can be safely ruled out as the problem.

You probably have packet loss on the network, wich thends to get worse quickly as more date is send trough the line. This would explain why the remote desktop seem to be unaffected, as it's reasonable light-weight traffic compared to file transfers.

- Open a ping from the machine accessing the UNC to the machine it is accessing it from. See if there are any problems. Now with the ping still open ( use -t on windows to keep it from quitting after 3 runs) start transfering data and see if if that has any effect on it.

- Errors caused by network connectivity can cause this. Mismatched MTU sizes or truncation of a packet at a router can result in this error when files larger than the largest packet size are copied over the network. In essence, the network connection is the media that has the physical problem.

Though this probably sounds strange, I have seen this before. It is usually resolved by deleting all cached network locations from "my network places". Just delete everything there. explorer seems to access those before doing anything else, wich tends to take a long time if there are connections to an nonexisting location or just a lot of working connections. Just  give it a try.
for more information about this, see . Also contains an more permanent solution, should this indeed be the cause.
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Try this command:

netsh int ip reset resetlog.txt

It has resolved many slow connections for me in the past. :)
also note the following (taken from the link above):

Similar issues affect the Start menu and Desktop - placing a shortcut to a network resource in either location can drastically slow down system response, particularly when the network resource is unavailable. Shortcuts to Domains or Machines don't suffer from these problems as they always have the same icon.


Method 1
Create a drive map and use this to browse the network files.

Method 2
Create a shortcut to explorer.exe and pass the UNC name of the resource.
explorer /e, \\Server\FileShare


A second issue that will also slow down browsing is the desktop.ini feature. This affects Windows XP Sp1 clients using mapped drives or UNC connections.

When listing a directory Windows XP will search for and parse Desktop.ini files. This will noticably affect performance when a large number of subfolders are involved - it does this for the current folder and one level down the directory tree.

Desktop.ini can be used to provide a custom icon, thumbnail view, pop up description and background pattern.
In additions to this 'eye candy' desktop.ini can make normal file folders into 'Special Folders' (eg Fonts, History, Temporary Internet Files, "My Music", "My Pictures", and "My Documents").

Desktop.ini files are only visible in Windows Explorer if you first un-check "Hide protected operating system files" (under Tools, Options, View)

To see the file locks created by this process run the following command on the file server, while an XP client is (slowly) listing a large directory:

    NET FILE | Find "desktop.ini"
    OPENFILES /s MyServer |Find "desktop.ini"

Also consider: AntiVirus software, DNS configuration, the NTFS volume (security descriptors & indexes) defrag and CHKDSK.

I had a similar problem, and solved it by enplementing WINS name resolution on all network areas.  Browsing my network places on a network or network segment without a WINS server results in broadcast name resolution, which on larger networks can have the effect you are describing.
RealwizAuthor Commented:
The problem is happening on different machines, different OS, and hardware, one of which I rebuilt from scratch just recently.  Same problem right out of the box.    I should also mention the fiber link has a media converter on each end, going into a copper port of each cisco switch.  The media converters are also set to Full Duplex 100Mbit.  No error lights are showing on the Media Converters.  No errors showing in statistics for both of the ports on the switches.

If I try to copy a file, I get the error that it cannot copy the file: Error performing inpage operation.
Did you resolve your issue? Let us know how, so others can learn from it!
RealwizAuthor Commented:
I determined that it was a bad Omnitron media converter on one end.  I swapped it out with a new one on one end and the problem went away.  Not sure exactly what the media converter was doing, if it was packet loss, or truncation.  I hooked up a Fluke to it and the Fluke said everything was fine.  But for some reason, windows was having problems.
I'm sending the media converter back to omnitron for repair, they usually do testing, I'll post what they find out.
I'm awarding the points to dlangr, since his response dealt with the network level, and that's what it ended up being.
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