Could not copy DLL - The process cannot access the file because it is being used by another process.

Hello,

I keep getting this error when I Build and Run my project:

Warning: Could not copy "obj\Debug\Solution1.dll" to "bin\Solution1.dll". Beginning retry 5 in 1000ms. The process cannot access the file 'bin\Solution1.dll' because it is being used by another process.
Error: Could not copy "obj\Debug\Solution1.dll" to "bin\Solution1.dll". Exceeded retry count of 10. Failed.
Error: Unable to copy file "obj\Debug\Solution1.dll" to "bin\Solution1.dll". The process cannot access the file 'bin\Solution1.dll' because it is being used by another process.

This sometimes happens after a few successful builds, but sometimes on the first build when I launch VS. My workaround so far is to do Build > Clean, then Build and Run again. Or close VS and open it again. Is there a more permanent fix? This thread seems to suggest that it may be a VS bug. Is it?

Thanks all.