> We use virtual pc on many of our machines. Most of them work, but some
> lost
> the network access (but have worked before without that error).
> Eg. the following message comes up: 'Access to the external network and
> host
> will be unavailable to all virtual machines using virtual networking.
> ....'
> We use Virtual PC 5.3.582.35 .
> The 'Virtual Machine Network Services' are present and checked in 'Local
> Area Connection Properties', but there seem to be no driver information,
> if
> you look under its properties.
>
> We have a service, which enables/disables the 'Virtual Machine Network
> Services' depending on the network the pc is placed in. This service uses
> the
> 'Iphlpapi' to do this. (The 'Virtual Machine Network Services' checkbox
> will
> be checked or unchecked as the result of that function.)
> Could it be, that this API deletes the driver somehow or do you know other
> ways, why the 'Virtual Machine Network Services' could stop to work?
>
> I'm not looking for a solution to fix the problem after it comes up. I
> want
> to know, what could cause the problem and how we can avoid this problem to
> come up in the future.

> 1.. Have you checked your event logs on both the physical host computer
> and virtual machine and see if it shows any additional errors such as
> network hardware issues, IP conflicts, or anything that is not normal?
> 2.. What OS is hosted on the Virtual PC virtual machines (VMs)? Are there
> any Windows NT 4.0 and below or Windows ME/9x OS? Are you using Windows XP Home? List all Windows OS.
> Also, is Java code that is being used that does any IP error handling?
> 3.. Have these problem ever happened on the physical boxes?
> 4.. Are you running a broadband or dsl/cable connection? I am trying to
> see if your cable or dsl modem requires some code for OS IP facilitation.
> You normally will not see this problem with Window 2000 Professional or
> Server OS and above.
> 5.. Are you running special application code or software on the VMs that
> could possibly cause IP configuration changes?
> When you get the chance, answer the above questions and I may be able to
> tell you why you are having the problem. As for the fix - simply install a
> clean version of the iphlpapi.dll on all your affected VMs and see if this
> does not fix your problem. Let me know if this works or not.

> Please read my answers I put directly in your text...
>
> "John Jordan" wrote:
>
>> 1.. Have you checked your event logs on both the physical host computer
>> and virtual machine and see if it shows any additional errors such as
>> network hardware issues, IP conflicts, or anything that is not normal?
> I havn't seen any errors which seem to be related to this problem.
>
>> 2.. What OS is hosted on the Virtual PC virtual machines (VMs)? Are
>> there
>> any Windows NT 4.0 and below or Windows ME/9x OS? Are you using Windows
>> XP Home? List all Windows OS.
> The Host System is always WindowsXP SP2.
> The Guest System is WindowsXP SP2 as well, just in some cases, it's
> Windows
> Server 2003 or Windows 2000.
>
>> Also, is Java code that is being used that does any IP error handling?
> Not as far as I know.
>
>> 3.. Have these problem ever happened on the physical boxes?
> The problem happens on the physical machines. The error message comes up,
> BEFORE running the virtual machine after starting the VirtualPC
> application.
> So VirtualPC itself knows, that the needed service/driver is missing
> somehow.
>
>> 4.. Are you running a broadband or dsl/cable connection? I am trying
>> to
>> see if your cable or dsl modem requires some code for OS IP facilitation.
>> You normally will not see this problem with Window 2000 Professional or
>> Server OS and above.
> Some users use dsl/cable connections, but most of the time, it is just the
> internal LAN.
>
>> 5.. Are you running special application code or software on the VMs
>> that
>> could possibly cause IP configuration changes?
> It doesn't matter what's placed on the VM, because the error is already
> shown after VPC start.
>
>> When you get the chance, answer the above questions and I may be able to
>> tell you why you are having the problem. As for the fix - simply install
>> a
>> clean version of the iphlpapi.dll on all your affected VMs and see if
>> this
>> does not fix your problem. Let me know if this works or not.
> Again: It doesn't matter what's placed on the VM, because the error is
> shown
> after VPC start. In addition to that: If I would replace the DLL after the
> error comes up, it wouldn't help. And before that, I cannot know, who will
> have the problem.
> The service, which is enabling/disabling the VPC'Bridge' is placed on the
> host system.
>
> Other tools, which could cause network interferences, are the personal
> firewall and a data-synchronization tool.