MSBuild stop working after each build by Alois Masanell

hello,
after each compilation with visual studio 2012 msbuild stop working and i have to restart visual studio manually.
i tried to reinstall visual studio, repair visual studio, reinstall windows with and without updates nothing worked.
here is the message shown in visual studio:
The operation cannot be completed because BeginBuild has not yet been called.

I have enabled/disabled multicore compilation same result
here is the error generated by msbuild:

UNHANDLED EXCEPTIONS FROM PROCESS 4832:
=====================
15/02/2013 00:29:42
System.FormatException: Input string was not in a correct format.
at System.Text.StringBuilder.AppendFormat(IFormatProvider provider, String format, Object[] args)
at System.String.Format(IFormatProvider provider, String format, Object[] args)
at Microsoft.Build.BackEnd.BuildRequestConfiguration.GetCacheFile()
at Microsoft.Build.BackEnd.ConfigCache.ClearConfigurations()
at Microsoft.Build.Execution.OutOfProcNode.CleanupCaches()
at Microsoft.Build.Execution.OutOfProcNode.HandleShutdown(Exception& exception)
at Microsoft.Build.Execution.OutOfProcNode.Run(Exception& shutdownException)
at Microsoft.Build.CommandLine.MSBuildApp.StartLocalNode(CommandLineSwitches commandLineSwitches)
at Microsoft.Build.CommandLine.MSBuildApp.ProcessCommandLineSwitches(CommandLineSwitches switchesFromAutoResponseFile, CommandLineSwitches switchesNotFromAutoResponseFile, String& projectFile, String[]& targets, String& toolsVersion, Dictionary`2& globalProperties, ILogger[]& loggers, LoggerVerbosity& verbosity, List`1& distributedLoggerRecords, Boolean& needToValidateProject, String& schemaFile, Int32& cpuCount, Boolean& enableNodeReuse, TextWriter& preprocessWriter, Boolean& debugger, Boolean& detailedSummary, Boolean recursing)
at Microsoft.Build.CommandLine.MSBuildApp.Execute(String commandLine)
at Microsoft.Build.CommandLine.MSBuildApp.Main()
===================
15/02/2013 00:29:42
System.FormatException: Input string was not in a correct format.
at System.Text.StringBuilder.AppendFormat(IFormatProvider provider, String format, Object[] args)
at System.String.Format(IFormatProvider provider, String format, Object[] args)
at Microsoft.Build.BackEnd.BuildRequestConfiguration.GetCacheFile()
at Microsoft.Build.BackEnd.ConfigCache.ClearConfigurations()
at Microsoft.Build.Execution.OutOfProcNode.CleanupCaches()
at Microsoft.Build.Execution.OutOfProcNode.HandleShutdown(Exception& exception)
at Microsoft.Build.Execution.OutOfProcNode.Run(Exception& shutdownException)
at Microsoft.Build.CommandLine.MSBuildApp.StartLocalNode(CommandLineSwitches commandLineSwitches)
at Microsoft.Build.CommandLine.MSBuildApp.ProcessCommandLineSwitches(CommandLineSwitches switchesFromAutoResponseFile, CommandLineSwitches switchesNotFromAutoResponseFile, String& projectFile, String[]& targets, String& toolsVersion, Dictionary`2& globalProperties, ILogger[]& loggers, LoggerVerbosity& verbosity, List`1& distributedLoggerRecords, Boolean& needToValidateProject, String& schemaFile, Int32& cpuCount, Boolean& enableNodeReuse, TextWriter& preprocessWriter, Boolean& debugger, Boolean& detailedSummary, Boolean recursing)
at Microsoft.Build.CommandLine.MSBuildApp.Execute(String commandLine)
at Microsoft.Build.CommandLine.MSBuildApp.Main()
===================
PS: sorry for my bad english