I have solution with 1 web project & multiple class library projects. I open solution, view code file & everythign is fine. I hit f5, & view the web site... I stop debugging.... then chaos. The IDE loses references for all the referenced project dlls in the bin folder & they light up red. I can compile & the project works fine If I debug again. If I uninstall reharper, this problem goes away. It cropped up somewhere around build 244 or 243 when the bogus duplicate reference bug went away. To get around it, I can build each subproject, then in the bin folder for web project, update reference for the dll... then close the .cs file and re-open it, and the object types will be picked up by the highlighter & intelisense. As soon as I hit f5 again & stop viewing the web site in debug mode, several of the referenced dlls from subprojects are highlighted red where tried to use in code & intellisense is lost on those objects.