I'm using vagrant with the latest winnfsd binary. The latest version still hasn't fixed crashes and hangs.

Usually after half an hour or an hour nfs hangs, even if in the log there is no failed operation. Sometimes it crashes completely, and sometimes the shared folders simply don't show up in the guest machine.

Vagrant 1.8.5
winnfsd.exe 2.2.0
all mount options default
windows 7 host, ubuntu 14.04 guest

I'm not sure what other info to give you to help debug.