Now you see it, now you don’t

I am having a weird network problem after I upgraded from XP to W7. I have 3 computers, 1 desktop and 2 laptops all running W7, plus a Dlink WBR-2310 router and a networked printer. The hardware has not changed from pre-W7 to post-W7. I was not getting this problem with XP. The printer and desktop are connected to the router via ethernet cables and the 2 laptops are wireless. All three computers have no problem connecting to the internet and connecting to the printer.

The problem is the computers have trouble seeing each other most of the time. Sometimes when I open the Network folder I can only see the computer I am at (plus the printer), if I refresh a few times I might see one or both the other computers. If I then open the Network and Share Center and select See Full Map I again may or may not see the other computers. Back in the Network fold if I double click one of the other computers I may get an error message saying “Windows cannot access \\XXXXXXX” or I may connect. When I can see the computer in the Full Map I can always connect. But most times one or both of the other computers will just not show up in the Network folder or the network map. Most of the time I can ping the other computers without any errors (see note below), but I still may or may not be able to access that computer.

I am running Workgroup not Homegroup and they all have the same Workgroup name.

Each computer has a unique IP address assigned by the router.

The problem seems random, sometime it works correctly, but most of the time it does not.

I have unchecked the TCP/IPv6 check box in the Network Connections Properties dialog box on all three computers. I have not disabled IPv6 as per KB929852

I have rebooted the router.

Sometime when I ping one of the computers I get the following response:
Reply from 192.168.2.101: Destination host unreachable
(Note- The IP address of my computer is 192.168.2.101, the IP address of the computer I am pinging is 192.168.2.103)

Any suggestions?

All three computers are using Microsoft's firewall. One laptop and the desktop are running Microsoft Security Essentials and the other laptop is running the Avast anti-virus.

All three computers are running Windows 7. All three are also set as a Home network. I have 2 computers running Windows 7 Pro and 1 running Windows 7 Home, so I cannot setup for a Work Network. I don't want to activate Homegroup because at times I have guests at the house that are running XP and Homegroup does not support XP (my understanding).

The Windows 7 is a new install so there is nothing to roll back to, the roll back option button is grayed out.

I would start by uninstalling Avast from the laptop.

I'm not sure why you can't set up a workgroup but that is usually what works best.

Did you actually upgrade from XP with the Windows 7 upgrade CD?

If so a clean install usually works better so it may be worth a try.

Clean Install with a Upgrade Windows 7 Version

I still have the problem when the laptop with Avast is powered off. Because the problem is intermittent I don't understand how it could be an antivirus or firewall issue.

One laptop is new and came from the factory with Windows 7 installed, the other two computers were clean installs, I reformatted the hard drives before installing Windows 7.

Can you share files or is the network map the only problem?

Most any A/V can cause sharing problems, yes intermittent ones also strange as it may seem. Usually when you can't see other machines there is an A/V involved.

When I can access another computer I can share files, but most of the time either the computer does not show up in the Network folder or if it does I cannot access it, I get a "Windows cannot access \\xxxxxxx" error.

I use the network map as a indicator, if the computer shows up on the network map I can access it, if it does not then I usually cannot access it.

Usually when I see these types of problems it's caused from A/V software or a third party firewall, the fact that it's intermittent makes it even more likely that an A/V is causing the problem.

I would start by turning IPv6 back on, that hardly ever fixes anything and if it does fix something it's only because another piece of hardware is outdated and not working properly.

It might help if you post a screen shot of your, ipconfig /all then hit enter, typed into a command prompt. This is just to insure that you are using a common default gateway.

It might also help to simply reset your router by pushing the reset button and see if things improve or not. There are quite a few complaints about your particular router at the Newegg review section. According to the posters there you should definately update the firmware on your router.

http://www.newegg.com/Product/Produc...82E16833127073