VS 2015 SSIS 2014 Error when opening or executing package in VS 2015

We have an SSIS package we've been developing in VS 2015 that's been opening in VS as we're working on it.  Suddenly yesterday when any of us try to even open the package in VS 2015, we get the following error:

Error loading 'SPHRIS_INTF0186_Daily_SAP_File_Update.dtsx' : The package failed to load due to error 0x80070057 "The parameter is incorrect.". This occurs when CPackage::LoadFromXML fails.
.  C:\TFS_Prod\HRIS\HRIS-SSIS\HRIS-SSIS\SPHRIS_INTF0186_Daily_SAP_File_Update.dtsx 1

When I right click and try to execute the package, the error message is expanded (but no clearer):

Error  System.ArgumentException: The package failed to load due to error 0x80070057 "The parameter is incorrect.". This occurs when CPackage::LoadFromXML fails.

   at Microsoft.SqlServer.Dts.Runtime.Package.LoadFromXML(String packageXml, IDTSEvents events)
   at Microsoft.SqlServer.Dts.Runtime.Project.LoadPackage(IProjectStorage storage, Package package, String streamName, IDTSEvents events)
   at Microsoft.SqlServer.Dts.Runtime.PackageItem.Load(IDTSEvents events)
   at Microsoft.SqlServer.Dts.Runtime.PackageItem.get_Package()
   at Microsoft.DataTransformationServices.Project.DataTransformationsProjectBuilder.IncrementalBuildThroughObj(IOutputWindow outputWindow)
   at Microsoft.DataTransformationServices.Project.DataTransformationsProjectBuilder.BuildIncremental(IOutputWindow outputWindow)   0

Can anyone shed some light on what might be happening?  Or at least point us in a direction where to begin to look?  2 of us are running Windows 10 and 1 Windows 7 but we all get the error for this package.

Thanks for any insight/help!