how to open xbap file?

how can I open .xbap file downloaded from internet? many Control vendor sites offers to download .xbap file to show WPF controls, but I cant Open them. Internet Explorer generates error:

http://img28.imageshack.us/i/capturenxs.png/

Error Log:

ERROR DETAILS Following errors were detected during this operation. * [3/31/2011 2:23:10 PM] System.Deployment.Application.InvalidDeploymentException (ManifestParse) - Exception reading manifest from file:///E:/Downloads/ControlExplorer.xbap: the manifest may not be valid or the file could not be opened.

• Source: System.Deployment - Stack trace: at System.Deployment.Application.ManifestReader.FromDocument(String localPath, ManifestType manifestType, Uri sourceUri) at System.Deployment.Application.DownloadManager.DownloadDeploymentManifestDirect(SubscriptionStore subStore, Uri& sourceUri, TempFile& tempFile, IDownloadNotification notification, DownloadOptions options, ServerInformation& serverInformat开发者_开发知识库ion) at System.Deployment.Application.DownloadManager.DownloadDeploymentManifest(SubscriptionStore subStore, Uri& sourceUri, TempFile& tempFile, IDownloadNotification notification, DownloadOptions options) at System.Deployment.Application.DeploymentManager.BindCore(Boolean blocking, TempFile& tempDeploy, TempDirectory& tempAppDir, FileStream& refTransaction, String& productName) at System.Deployment.Application.DeploymentManager.BindAsyncWorker() --- Inner Exception --- System.Deployment.Application.InvalidDeploymentException (SignatureValidation) - Manifest XML signature is not valid.

• Source: System.Deployment - Stack trace: at System.Deployment.Application.Manifest.AssemblyManifest.ValidateSignature(Stream s) at System.Deployment.Application.ManifestReader.FromDocument(String localPath, ManifestType manifestType, Uri sourceUri) --- Inner Exception --- System.Security.Cryptography.CryptographicException - No signature was present in the subject.

• Source: System.Deployment - Stack trace: at System.Deployment.Internal.CodeSigning.SignedCmiManifest.Verify(CmiManifestVerifyFlags verifyFlags) at System.Deployment.Application.Manifest.AssemblyManifest.ValidateSignature(Stream s)

Do you have .Net 3.5 SP1 installed? The original version of 3.5 did not allow unsigned applications.