"Value cannot be null" error when trying to edit or create Maintenance Plan in SQL Server 2008

Question

I have SQL Server 2008 installed on Windows Server 2008 64bit, every time I try to open or create a new Maintenance Plan I receive the error:
Value cannot be null.
Parameter name: component (System.Design)
Program Location:
   at System.ComponentModel.Design.DesignerHost.System.ComponentModel.Design.IDesignerHost.GetDesigner(IComponent component)
   at Microsoft.DataTransformationServices.VsIntegration.DtsDesignerService.OpenDesigner(String connectionString, Object connection, String objectUrn)
   at Microsoft.SqlServer.Management.DatabaseMaintenance.MaintDesignerMenuHandler.Invoke()
And in the Design view screen
"Microsoft SQL Server Management Studio is unable to load this document: Could not load type 'Microsoft.SqlServer.Dts.runtime.Wrapper.IDTSPackageSigning100' from assembly 'Microsoft.SqlServer.DTSRunTimeWrap, Version=10.0.0.0, Culture=neutral'. 
I have searched for a possible solution and have tried some suggestions of registering the msxml6.dll but and have installed VS2008 SP1 but I'm not in a position where I can do a full reinstall of SQL Server right now. Any help is appreciated. My SQL server
environment information is below. 
Microsoft SQL Server Management Studio
10.0.1600.22 ((SQL_PreRelease).080709-1414 )
Microsoft Analysis Services Client Tools
2007.0100.1600.022 ((SQL_PreRelease).080709-1414 )
Microsoft Data Access Components (MDAC)
6.0.6002.18005 (lh_sp2rtm.090410-1830)
Microsoft MSXML 3.0 4.0 5.0 6.0 
Microsoft Internet Explorer 8.0.6001.18943
Microsoft .NET Framework 2.0.50727.4206
Operating System 6.0.6002

Answer 1

I digged a little deeper and figured out it was a missing directory/file in %TEMP%. Seems some CleaningTool removes all files/directories in %Temp% and after that SSMS was not working any longer. The missing file is actually not needed, but the
missing directory causes the "Value cannot be null" error.
My missing file name was:
C:\Users\<username>\AppData\Local\Temp\2\6vvdaozf.tmp
But the file name changes on every startup.
So my missing directory name was:
C:\Users\<username>\AppData\Local\Temp\2
After creating a empty directory with the name "2" in %TEMP% all went back to work fine for me.
I'm not sure the directory name is every time the same, but you can discover your missing file with the process monitor from Sysinternal Tools and filters to "Process Name is ssms.exe" and "Path contains AppData\Local\Temp"
Hope this helps other people to solve their issues too.
Thank you!! When I run %temp% it takes me to "C:\Users\Admin ...~\AppData\Local\Temp\some random number". At first the random number was 3, after I logged off and back on it was 2. My temp variable in enviromental variables is correct. I looked on another machine
running SQL2008 and temp is correct there. If I try to rename the numbered folder SSMS stops working. Any idea?