What does the error "The AssertApplicationRequirements method either did not get called or timed out. There is no trust decision before the commit." mean

Hello,

I have a XBAP application developed using Microsoft .NET Framework 3.5. On several computers where the application functioned up until today, ClickOnce displays the following error when new users try to download the application:

ERROR SUMMARY
 Below is a summary of the errors, details of these errors are listed later in the log.
 * An exception occurred while downloading the application. Following failure messages were detected:
  + The AssertApplicationRequirements method either did not get called or timed out. There is no trust decision before the commit.

COMPONENT STORE TRANSACTION FAILURE SUMMARY
 No transaction error was detected.

WARNINGS
 There were no warnings during this operation.

OPERATION PROGRESS STATUS
 No phase information is available.

ERROR DETAILS
 Following errors were detected during this operation.
 * [7/15/2013 5:58:14 PM] System.Deployment.Application.DeploymentException (Unknown subtype)
  - The AssertApplicationRequirements method either did not get called or timed out. There is no trust decision before the commit.
  - Source: System.Deployment
  - Stack trace:
   at System.Deployment.Application.DeploymentManager.WaitForAssertApplicationRequirements()
   at System.Deployment.Application.DeploymentManager.SynchronizeCore(Boolean blocking)
   at System.Deployment.Application.DeploymentManager.SynchronizeAsyncWorker()

COMPONENT STORE TRANSACTION DETAILS
 No transaction information is available.

What does this error mean? How can I trace the problem and correct it?

Thank you.

Cosmin Petrenciuc