While working on a variant of zip or map2 on Quad Ropes, I ran into the msbuild process hanging up multiple times. This makes a quick edit-compile cycle impossible because the only way to kill the processes is a re-start of the machine.

Turns out that this is caused by parallel compilation. msbuild.exe keeps some processes around for later re-use. Turns out this sometimes causes locking of files such that re-compilation becomes impossible. What a great feature.

Anyways, Jon Rea has posted on Stackoverflow about this and his answer explains everything in much more detail.