I've had an IIS 7.5 server running for about a month, but I suddenly noticed that FTP seems to hang. This is best demonstrated in the DOS ftp client.
C:\Documents and Settings\jhoge>ftp FTPSite.com Connected to FTPSite.com. 220 Microsoft FTP Service User (FTPSite.com:(none)): UserName 331 Password required for UserName. Password: 230 User logged in. ftp> dir [...server hangs here for about a minute ...] Connection closed by remote host.