When the explorer shell is first launched it attempts:
SystemRoot%\Explorer.exe /idlist,%I,%L
/IDLIST
This is an additional parameter that means a Windows internal structure is being passed. eg:
Explorer.exe /e,/idlist,%I
The %I is a replacable parameter representing an IDLIST.
%L is a long file name or in your case a directory path.
I think DestinysDream is on the right path. Open up again the user profile and explicitly make sure the profile path is empty or set exactly as you want. There can be null or ASCII values > 127 characters there.