Windows 7 Service Pack 1 Resolves Network Dropouts

A few months back, I purchased a Lenovo ThinkPad Edge running Windows 7 Professional 64-bit. From the beginning, I had frequent issues with applications crashing due to lost connections to the server.

This happened with “legacy” database applications like GoldMine 6.5, but also with newer applications that are supposed to support 64-bit Windows 7 like Commit CRM and QuickBooks Pro 2010. Most frequently, the disconnects would happen after a period of inactivity, e.g. I would come in in the morning and find that applications had crashed.

I had used most of these apps on the same network under Windows XP (Dell Dimension) and 32-bit Windows 7 (Lenovo ThinkPad T60p) without issue, so I was pretty sure the network and the server were fine, and that the problem was specific to the new laptop.

The event log often included messages about Delayed Write Failed. I also found a special NetworkProfile event log that documented the repeated disconnects and reconnects, with this series of events occurring several times a day:

Log Name:      Microsoft-Windows-NetworkProfile/Operational
Source:        Microsoft-Windows-NetworkProfile
Date:          6/17/2011 8:16:15 PM
Event ID:      10001
Task Category: None
Level:         Information
Keywords:      (35184372088832)
User:          LOCAL SERVICE
Computer:      Laptop01.mydomain.local
Description:
Network Disconnected
    Name: mydomain.local
    Desc: mydomain.local
    Type: Managed
    State: Disconnected
    Category: Domain Authenticated

Log Name:      Microsoft-Windows-NetworkProfile/Operational
Source:        Microsoft-Windows-NetworkProfile
Date:          6/17/2011 8:16:16 PM
Event ID:      4002
Task Category: Wait for Identification
Level:         Information
Keywords:      Response Time,(35184372088832)
User:          LOCAL SERVICE
Computer:      Laptop01.mydomain.local
Description:
Transitioning to State: Identified Network Interface Guid: {9c2ed054-3161-43e7-1bc6-6d279b7f6c51}

Log Name:      Microsoft-Windows-NetworkProfile/Operational
Source:        Microsoft-Windows-NetworkProfile
Date:          6/17/2011 8:16:16 PM
Event ID:      10000
Task Category: None
Level:         Information
Keywords:      (35184372088832)
User:          LOCAL SERVICE
Computer:      Laptop01.mydomain.local
Description:
Network Connected
    Name: mydomain.local
    Desc: mydomain.local
    Type: Managed
    State: Connected,IPV4 (Internet)
    Category: Domain Authenticated

Attempted Fixes

I tried all kinds of things trying to get this to work. This ThinkPad Edge uses a Realtek PCIe GBI Family Controller (NIC). Here’s some of what I went through:

• Turn off wireless NIC (isolate to wired NIC).
• Upgrade to latest NIC driver from Realtek.
• Set application compatibility mode to XP SP3 using a batch file (MSKB 286705)
• At the request of Lenovo support, downgrade NIC driver to Lenovo’s latest, from 2009.
• Turn off NIC power management.
• Turn off NIC green Ethernet.
• Force NIC to use 100Mbps rather than Auto-negotiate.
• Disable IPv6 on client.
• Upgrade entire infrastructure to gigabit (new Cat6 cables, new Cisco switch).
• Replace NIC (required replacing motherboard).
• Upgrade NIC driver on server.
• Upgrade again to latest NIC driver from Realtek.

None of this solved the problem; applications continued to get disconnected and crash.

Final Fix?

About a week ago, I installed Windows 7 Service Pack 1. This seems to have finally resolved the issue. Desktop applications that require a constant connection to the server do not frequently crash; I can leave apps running overnight and pick up where I left off in the morning.

IPv6 is still turned off on the client—I have not tested it with IPv6 turned on.

I still get the network dropout messages in the event log. But somehow the apps are now able to bridge the brief lost connection.

So it seems that some bug in Windows 7 was causing the problem, and that the bug was fixed with Service Pack 1. It would be nice to know exactly which fix helped, but for now I’m just glad things are fairly stable once again.