There is a bug in the 1.1 release where the working directory is not set for an initial project build. This leads to an exceptions like:

INTERNAL ERROR: Value cannot be null.
Parameter name: path1
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System.ArgumentNullException: Value cannot be null.
Parameter name: path1
   at System.IO.Path.Combine(String path1, String path2)
   at ThoughtWorks.CruiseControl.Core.IntegrationResult.BaseFromWorkingDirectory(String pathToBase)
   at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vault317.VersionHistoryProcessInfo(IIntegrationResult from, IIntegrationResult to, Boolean bForceGetLatestVersion)
   at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vault317.GetFolderVersion(IIntegrationResult from, IIntegrationResult to)
   at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vault317.LookForChangesUsingVersionHistory(IIntegrationResult from, IIntegrationResult to)
   at ThoughtWorks.CruiseControl.Core.Sourcecontrol.Vault317.GetModifications(IIntegrationResult from, IIntegrationResult to)
   at ThoughtWorks.CruiseControl.Core.Sourcecontrol.VaultVersionChecker.GetModifications(IIntegrationResult from, IIntegrationResult to)
   at ThoughtWorks.CruiseControl.Core.Sourcecontrol.QuietPeriod.GetModifications(ISourceControl sourceControl, IIntegrationResult lastBuild, IIntegrationResult thisBuild)
   at ThoughtWorks.CruiseControl.Core.IntegrationRunner.Integrate(IntegrationRequest request)
   at ThoughtWorks.CruiseControl.Core.Project.Integrate(IntegrationRequest request)
   at ThoughtWorks.CruiseControl.Core.ProjectIntegrator.Integrate()
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The workaround is to copy a state file from a project which has built successfully and change the version number back to 1.