Missing network drives

I am seeing the following :

15,000 XP Clients, Win2k AD backend.
Intermitantly, drive mappings dissapear as follows
Not visible in My Computer
Still visible in Explorer but drive name is corrupt and file type identified as raw
Still visible at cmd prompt.
Killing and restarting explorer.exe resolves issue.

We have a MS Premier contract but MS and ourselves are struggling to replicate this issue.
Has anyone else seen this issue? Better still, fixed it? I am after an explicit answer - simply deploying XP SP1 is not viable.

500 points to someone with the answer.....

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Have you tried another brand of ether card in the win2K machine?
Is the mobo up-2-speed on the chip updates?
Help me understand the problem...

You've got 15,000 clients that are all experiencing a problem with dissappearing drive mapping?   Are they all mapped to the same server (or does the target resource not have a bearing on the problem).   Are they all in the same domain... same OU, etc

I presume this is a Win2k "native mode" domain where network resources are "advertised" in Active Directory as well as available for the picking thru the Network Neighborhood/My Network Places?

How are these mapped drive created?  A login batch?.. by hand, by application?... is the "persistent" flag set?

Why are you using mapped drive letters at all?  If all your clients are WinXP, why not use UNC path's instead (just curious)
There is a reg setting that tells the servers to disconnect clients after n minutes of inactivity. I think by default it is set to 15 minutes but the setting is in seconds so 900 seconds. Last time I looked at this, there was a ceiling to the time you can set. The alternate option was to set to -1 which was unlimited, but then all of the dynamic server setting adjustments that Windows can perform gets set statically. While I've typically seen the red X symptom, if the drive mappings aren't persistent, I'm wondering if they just wouldn't get removed.

Check this article out. If it's not the answer, let me know if you do figure this out.


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The problem with disappearing and reappearing resources such as drive mapping can occur during the process of master browser election.  During this period service ceased to broadcast.  If you have a dual-home (two NICs) server - see my previous responses on this issue below.

If you don't have a dual-home server, check to see why your networking is forcing a master browser relection.  Is the network traffic too heavy?  Is the server too busy?  Is there a faulty cable or NIC in the server?  How many server do you have that you forgot to accounted for ie... Exchange, etc???


Here are my previous posts: ********************
Your problem is in dual-home server.  It's a known problem - what's happening is the master browser election taking place and causing the network resources to disappear so clients are not able to access the resources until the election is complete and the client can see the resource again.  (Added) Meanwhile, the clients have to wait.... so network appears a very slow........ It takes minutes to logon and minutes to access anything.....

Here are my previous answers to the problem:


Here is the MS knowledge base article and how to deal with it:

sweatbeastAuthor Commented:
Thanks all for responses.

Let me clarify - the drive mapping is still available via command line. It is available within windows explorer but the label is corrupt and the filesystem is identified as RAW. From My Computer it is not available.

Networking itself is not dropping out - connectivity via a UNC to the same host is fine. However, interestingly, file copy results in an error stating that the target does not suppot long file names, so you have to shorten to 8.3 format.
Killing and restarting Explorer.exe fixes the problem.
This occurs to random users at random times.
And what about the event logs?
Killing and restarting on the host or server side?
Try to replace the NIC on the server and possibly the protocol stack.....

sweatbeastAuthor Commented:
No entries written to Event log on client or server.
Network drives hosted on several different servers; not server specific.
Check for a common router/switch/bridge that these workstations are using.  One of them may have bad memory corrupting packets....


How is it going?

cheers / Gnart
sweatbeastAuthor Commented:
This is happening enterprise wide, utilising many different routes with no common denominator on the network side.
I too have this issue. Red X condition on mapped drives but UNC path through explorer works. I found some info indicating that it may be DNS related so I bounced my internal AD integrated DNS server and the drives came back. I do occasionally see  browser election issues but I'm not sure that is the issue.


Adding on th brianperry's post.  Install network monitor on the machine that usually exihits the problem.  WHen the problem occurs, try to access through the problem and look at the traffic log.  Then, access through the \\UNC and compare the traffic log... to see if its a DNS/WINS issue.

I have a client with the same issue.
In explorer some network drive letters are missing or the name is corrupt.
The drives can be accessed from the run or command prompts.
A simple NET USE from the command prompt will show all the drives are mapped properly.

This is the information I have found so far:
Microsoft "Drive Letters of Mapped Network Drives Are Missing in Windows Explorer"
Has a patch you have to contact MS for. (Should be free though)

Another suggestion is that the machines may have TweakUI on them which can hide drive letters.  This may be a bug in it as the article doesn't suggest you can fix it, but simply remove it if installed.  TweakUI is a MS PowerToy/Tool.

Finally,  there is another possiblility.  Does your company use and spyware to monitor employees?  If so this also may be the culprit as some of them have the ability to hide drive letters and may cause this type of error.

Let me know if any of this succeeds.

Good luck.
PAQed - no points refunded (of 500)

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Greetings sweatbeast and All,

I to am having the same issue. It is site wide with 1,200 users.

The issue maifested itself after we made two changes. Cicso Router and Switch upgrades and IP Scheme Changes.

Here are the IP schemes:

192.168.50.x = Server Subnet
192.168.51.x = Client Subnet
192.168.52.x = Client Subnet
192.168.53.x = Client Subnet
192.168.54.x = Training Subnet

* All workstations are Win2k Pro
** All Servers are Win2k Server and Win2k3 Enterprise.

Symptoms are Mannped Drives Randomly disconnect and hourly Master Browser elections from workstations from different subnets.

Temporary Workaround:

I can turn off Browsing on the workstations that are calling for elctions in the AD2k3 domain controllers and is resolves the issue until more workstations start up the elections. If I let it go for 2 days, we start all over with Mapped Drives Disconnects.

WINS and DNS services are working perfect with no events issues in the WINS and DNS servers.

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