A issue run Windows 2008 as guest os on Microsoft Virtual Server 2

I have a windoes 2003 host, which is MS Windows Server 2003 R2 Enterprise
with Service Pack 2. In this host, I installed Microsoft Virtual Server 2005
R2 SP1 with Update KB948515 (Virtual Server version 1.1.629.0 EE R2 SP1 ).

On Virtual Server 2005, I setup a VM for Windows Server 2008 Standard with
Service Pack 2. And in this VM, a web site based on IIS 7 is running for
testing.

But every several hours, the web site has a Request time out error.

Server Error in '/test' Application

Request timed out

Description: An unhandled exception occurred during the execution of the
current web request. Please review the stack trace for more information about
the error and where it originated in the code.

Stack Trace:

[HttpExeception (Ox80004005): Request timed out.]



Restart this VM can fix this issue. I also run this web site on a Windows
2008 on a real server. Everything is fine.

So I think this is a Virtual Server 2005 issue.

How can I fix this? Thanks a lot.