Windows 7 is not supported - you need to install this on Windows Server 2008 R2 64-bit, RTM or SP1.  See the Platform and Support Matrix here:
 http://www.symantec.com/docs/HOWTO9965

If you were to have the correct OS and still see this error, I would recommend that you ensure you aren't behind a proxy (or if you are, you've configured it correctly).  You could also install the suite solution by solution rather than selecting the entire suite at once, of course beginning by installing the Symantec Management Platform under 'Platform' and then to the solutions under 'Solutions.'

Does this help?

You would require a server oprating system to install the Suite or SMP. I am not sure how did you get SIM to work on windows 7.

I tried to install SMP and CMS 7.1 SP1 in a "new Server" the last Friday and I had the same problem.

I was working on Windows Server 2008 R2 64 bits and once it is done downloading all of the files Progress changes to "Validating files" o something like that and it always end with the same error message.

I tried to download the file three times and I got the same message. So I only installed the SMP 7.1 SP1 and left the installation in Standby.

I checked the size of the files and they are very similar to another of 7.1 SP1(a) installation that I have.

Any suggestion?

I too am having the same problem (or it is just the same error message).  I'm using Windows 2008 R2.  Anyone find a solution.  I checked the install log and I think it is timing out when downloading a file.

<event date="Nov 21 14:26:49 +00:00" severity="4" hostName="HOSTNAME" source="Symantec.Installation.FileDownloader.DownloadFile" module="SymantecInstallationManager.exe" process="SymantecInstallationManager" pid="4528" thread="84" tickCount="582391437"><![CDATA[DownloadFile - Downloading file from 'http://www.solutionsam.com/solutions/7_1/itms/7_1_sp1_mr1_rtm/altiris_deploymentsolutiontaskserverhandler_7_1_x64.msi?symct=1321893501_c1d313fdc915d27361ea39258b432323' to 'file:///C:/Program Files/Altiris/Symantec Installation Manager/Installs/Altiris/altiris_deploymentsolutiontaskserverhandler_7_1_x64.msi']]></event>
<event date="Nov 21 14:28:29 +00:00" severity="1" hostName="HOSTNAME" source="Symantec.Installation.FileDownloader.DownloadFile" module="SymantecInstallationManager.exe" process="SymantecInstallationManager" pid="4528" thread="84" tickCount="582491453"><![CDATA[DownloadFile - No response was received during the time-out period for a request.

( Exception Details: System.Net.WebException: The operation has timed out
   at System.Net.HttpWebRequest.GetResponse()
   at Symantec.Installation.FileDownloader.DownloadFile(Uri sourceUri, Uri destinationUri, Int64 fileSize) )
( Exception logged from:
   at Altiris.Diagnostics.Logging.EventLog.ReportException(Int32 severity, String strMessage, String category, Exception exception)
   at Altiris.Diagnostics.Logging.EventLog.ReportException(String strMessage, Exception exception)
   at Symantec.Installation.FileDownloader.DownloadFile(Uri sourceUri, Uri destinationUri, Int64 fileSize)
   at Symantec.Installation.FileDownloader.DownloadFiles()
   at Symantec.Installation.Context.WizardProcess.DownloadManager.FileValidationComplete(Object sender, FileValidationCompleteEventArgs e)
   at Symantec.Installation.FileValidator.ValidateFiles()
   at Symantec.Installation.Context.WizardProcess.DownloadManager.ValidateFiles()
   at Symantec.Installation.FileDownloader.DownloadFiles()
   at Symantec.Installation.Context.WizardProcess.DownloadManager.FileValidationComplete(Object sender, FileValidationCompleteEventArgs e)
   at Symantec.Installation.FileValidator.ValidateFiles()
   at Symantec.Installation.Context.WizardProcess.DownloadManager.ValidateFiles()
   at Symantec.Installation.Context.WizardProcess.DownloadManager.<>c__DisplayClass1.<BeginDownloadAndValidateFiles>b__0()
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()
 )
( Extra Details:  Type=System.Net.WebException Src=System )]]></event>
<event date="Nov 21 14:28:29 +00:00" severity="4" hostName="USDCA-SMPDEV01" source="Symantec.Installation.FileDownloader.DownloadFile" module="SymantecInstallationManager.exe" process="SymantecInstallationManager" pid="4528" thread="84" tickCount="582491453"><![CDATA[DownloadFile - Downloading file from 'http://www.solutionsam.com/solutions/7_1/itms/7_1_sp1_mr1_rtm/altiris_deploymentsolutiontaskserverhandler_7_1_x64.msi?symct=1321893501_c1d313fdc915d27361ea39258b432323' to 'file:///C:/Program Files/Altiris/Symantec Installation Manager/Installs/Altiris/altiris_deploymentsolutiontaskserverhandler_7_1_x64.msi']]></event>

When I recevied that error I clicked OK and the install continued.

Before that I did change the file used for product listings.

1. Click Settings
2. Click Change Product Listing
3. Click Add
4. Use the same URL except remove the .zip extension.