Hi
Was over on the Visual Studio support centre and they directed me here.
Running VS 2012 with all the latest updates. I think this used to work fine in VS2012 before any updates but it definitely worked fine in VS2010.
Basically, I have a website which references assemblies from another class library project of mine. If I update that assembly, I usually just rebuild my website and the latest version of the assembly was pulled through. I can't remember with VS2012, but in VS2010 I could simply just click Start or Build, Rebuild wasn't even required. Anyway, if I rebuild the website in my version of VS2012, it takes just as long as a normal rebuild, but with no effect. After rebuilding a second time, then it works.
I realise that I can click the Refresh button on the website references page to get the same effect, but further to the problem above, what I've also found is that when I place controls on a webform, the code-behind does not always pick the controls up. Then I need to recompile the site twice before it does.
Same happens with errors that have already been fixed. Only disappears after 2nd rebuilt.