Abandoned by Intellisense

This morning I was already to get to work on a fun programming project in Visual Studio 2005, but I had lost intellisense which is very annoying. I toggled between ReSharper's version and Microsoft's. I quit VS2005 and reopened. I checked in the recalcitrant file, checked it back out. Nothing.
Finally I closed all open windows, quit VS again, and Intellisense returned.
Which reminds me of a haiku,

Yesterday it worked. 
Today it is not working. 
Windows is like that.