The old find in files error

Sometimes when I try FindInFiles in Visual Studio, I can get this error:
"No files were found to look in.Find was stopped in progress." in Visual Studio 2003, 2005 and now also in 2008
...the solution is to press Control + Scroll Lock.

I used to believe VisualAssist had something to do with it, but in VS 2008 I only use ReSharper, so I suppose Visual Studio itself is the problem?