I have been having odd locking issues when using solutions that have  a c# project that is referenced by a c++/cli project.  This would happen in  VS 2003 and VS2005.  What could cause this horrid behavior?  Intellisense.  It has been locking the C#/VB output file while it updates.  Which means no building of the solution. 

While I am on Intellisense I have found many things in VC require it.  You need Intellisense to go to declarations and definitions, you even need it for the winforms designer to work.  Yet it is so utterly broken a large project will take any system to its knees with every press of the space bar.