Visual Studio cannot load few projects

"C:\Users\Administrator\Downloads\nopCommerce_2.10_Source\build\nop.proj
" (Deploy target) (1) ->
"C:\Users\Administrator\Downloads\nopCommerce_2.10_Source\NopCommerce.sl
n" (default target) (2) ->
"C:\Users\Administrator\Downloads\nopCommerce_2.10_Source\Presentation\N
op.Web\Nop.Web.csproj" (default target) (53) ->
(_CopyFilesMarkedCopyLocal target) ->
  C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets
(3001,9): error MSB3021: Unable to copy file "C:\Users\Administrator\Dow
nloads\nopCommerce_2.10_Source\Libraries\Nop.Services\bin\Release\Nop.Se
rvices.pdb" to "bin\Nop.Services.pdb". The process cannot access the fil
e 'bin\Nop.Services.pdb' because it is being used by another process. [C
:\Users\Administrator\Downloads\nopCommerce_2.10_Source\Presentation\Nop
.Web\Nop.Web.csproj]

49Warning(s)
1 Error(s)