Can not access network computers anymore

Last Thursday (03/05/12) I got a new computer to be able to work from home. I plugged it, by cable, into the company network and installed most of the software needed for me to do so, by accessing a share on my stationary computer at work. I had no issues here what so ever, and everything just worked.

Yesterday evening I tried accessing the company network trough Windows VPN, and while I was able to connect to the network, I was unable to connect to any computers on the network. I did, however, get an error when connecting, but I can't seem to get the error again, to get the details of the error message.

Today I am sitting on the company network again, and now I can not access anything on the network like I could last Thursday, though I can ping all the computers I am attempting to access.

Here is a list of details that might help in troubleshooting this issue (updated):

List of observations / actions

• My computer is identical to another computer that has no issues.
• It is not on the domain but rather on the default workgroup, but this was not an issue last Thursday, so I am assuming it still is not.
• I am able to access my e-mail on the exchange server.
• I can connect to our TFS server from Visual Studio but not from Explorer.
• I can also connect to Database Servers and Remote Desktop.
• I can see several computers when browsing network computers, but I am unable to connect to any of them.
• When trying to connect to a computer I am consistently met with the error code "0x80070035" (network path not found).
• I also get the 0x80070035 error when double clicking the target computer from the Network UI.
• I am not met with a login dialog when trying to access a computer, as I should, since I am not on the domain. (I did login to both Exchange, Remote Desktop and TFS though)
• Between Thursday where it worked and Sunday evening where it did not, I have installed quite a few security updates, plus various tools etc. that I need for programming.
• I have tried accessing by computer name and ip and neither of them work.
• I can ping by computer name.
• I have deleted all (1 entry) stored network credentials.
• I am able to access my computer from the target computer.
• Client and Server can see each other on the network = Network Discovery is enabled.
• I am using the network profile "Work".
• When accessing the network through VPN, I am unable to get anything to work using computernames, but all of the above applies when using IP adresses instead of computername.
• I run Windows 7 Home Premium on my computer.

Using powershell attempting to access a share I get the following error (ComputerName and ShareName being correct values of course):

PS C:\Users\MyUser> cd \\ComputerName\ShareName
Set-Location : Cannot find path '\\ComputerName\ShareName' because it does not exist.
At line:1 char:3
+ cd <<<< \\ComputerName\ShareName
    + CategoryInfo : ObjectNotFound: (\\ComputerName\ShareName:String) [Set-Location], ItemNotFoundException
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.SetLocationCommand

However, ping'ing the same machine (ping ComputerName) from powershell I get response immediately.

(As mentioned in the list of observations/actions, I tried the above with the IP address again on VPN, to get the same result)

Conclusion

So to sum up, pretty much the only thing I can not do, is access the other computers through browsing (explorer.exe, powershell, map networkdrive, etc.), which means that I am pretty much down to, that it is unable to resolve the path somehow, when trying to connect to other computers trough browsing, though the path gets resolved perfectly using all kinds of other services.

Any recommendations as to what I can try next to resolve the issue? :)

As I understand you are unable to access shared folders on other computers. Try completely disabling windows firewall for all profiles and see if you can browse the pc's. If you have some antivirus or firewall software, also try disabling it. Check your file and print settings in network and sharing center - > advanced sharing settings.