visual studio 2012 - VS2012 missing compiler errors in error list after upgrade from vs2010 -

just upgraded visual studio 2012, connected tfs solution, upgraded projects v4.0 v4.5. solution compiles , runs fine. super.

now i'm adding new code compiler errors not listed in error list output window. see errors related .dll files not being found.
e.g. error 1 not copy file "c:\sourcecode\<snip>library.dll" because not found. c:\windows\microsoft.net\framework\v4.0.30319\microsoft.common.targets

well of course can't found, put line:

thing bob = new thing(); 

into class.
unfortunately error not reported during compilation.
detailed comiler output shows nothing after csc.exe task:

6>task "csc" 6>  c:\windows\microsoft.net\framework\v4.0.30319\csc.exe <snip> 6>done executing task "csc". 

if run csc.exe task in cmd window can see exception:

microsoft (r) visual c# compiler version 4.0.30319.17929 microsoft (r) .net framework 4.5 copyright (c) microsoft corporation. rights reserved. state\conditionalaction.cs(16,13,16,18): error cs0246: type or namespace name 'thing' not found (are missing using directive or assembly reference?) state\conditionalaction.cs(16,29,16,34): error cs0246: type or namespace name 'thing' not found (are missing using directive or assembly reference?) 

has seen problem before or have ideas?

edit more evidence

it seems 'hard' compile errors being reported i.e. removing semi-colon line of rubbish gives me compiler error:

thing bob = new thing()

error 2 ; expected c:\\conditionalaction.cs 16

the error missing type, however, still not present.
edit 2 more evidence

it appears vs 2012 unable correctly identify project has error missing type when starting run , debug mvc app (f5). removed offending code, ran app, re-inserted offending code, re-ran app , vs merrily ran previously-compiled version of application without complaint.

i have had problems visual studio, when upgrading visual studio professional 2012.

firstly, checking fundamentals.

1. are using computer user administrative rights? suspect are, if not, need have administrative rights.

2. have checked if files being blocked firewall? when switched full version of avast find have disable file system shield loves remove executable files when try run visual studio projects.

3. ensure creating projects in 4.5 framework.

what did, ended uninstalling associated both visual studio downloads. if able remove , save project files elsewhere , bring them back. go through program files see if there hidden in wrong folder , check c drive.

which meant downloading , reinstalling (fresh):

1. install windows 7 service pack 1

2. visual c++ 2012 redistributable package (arm.exe, x64.exe , x86,exe)

3. microsoft .net framework 4.5

4. microsoft visual studio 2012 sdk

please read quote msdn visual studio 2012 update 3

note visual studio , team foundation server (tfs) installation mechanics different. visual studio update installs on top of whatever installed on computer. tfs update full layout replaces whatever installed on computer. before try apply tfs update, make sure have full backup of current databases. if tfs update installation fails, unable restart update or roll earlier version of tfs without performing restore procedure.

go page more information visual studio 2012 update 3.

here useful link configuring programs 64-bit (visual c++).