Blocked references in Visual Studio

Sometimes, when you try to compile project for DotNetNuke in Visual Studio it can not to do this. Error says: can't rebuild, because .dll of the project is locked. Sometimes it was real headache for me, because was really unexpected and unusual. First time i thought its problem with IIS, but later i found its problem with Visual Studio references. So, there are 4 steps to fix this issue:

1) Remove all references from your project (or whole solution). Try to rebuild - it shows errors, because can't find references.

2) Close Visual Studio.

3) Open solution and add all references.

4) Rebuild solution. It works now.

Hope this helps.