Unable to copy from obj\debug to bin\debug

Arrrrgghgghgh this problem reared its ugly head again today.  Occurs whenever I try to build a solution (winforms) on Visual Studio 2010.

Previously adding this to the build events (My project, compile tab, click build events):
If exist "$(TargetPath).locked" del "$(TargetPath).locked"

But after working for ages I started getting the error again.  Found this online though, and added it and looks like we are good again:

If exist "$(TargetPath).locked" del "$(TargetPath).locked"
if not exist "$(TargetPath).locked" if exist "$(TargetPath)" move "$(TargetPath)" "$(TargetPath).locked"

Microsoft really want to sort this out, as developers typically build a solution more than once, can’t quite get the hang of perfect coding 1st time round yet.