The way I've reproduced this:
1 make a new folder on Solaris
2 create a fifo file using "mknod ./test p" in your new folder on Solaris
3 create a new folder in windows
4 open each folder in WinSCP 5.5.5 running under windows 7
5 click the synchronize button
6 switch to local and leave the other settings at default and hit ok
7 the synchronization checklist will just have the fifo file copying to windows so hit ok
The "synchronization" window pops up, but The main window and the synchronization are immediately rendered unresponsive. With the time elapsed never getting past 0:00:00. I either kill it or wait until 90 seconds pass and the "Host is not communicating for more than 90 seconds" error pops up.
I don't know if the network error is caused by WinSCP or the host, but any operation that can take 90 seconds should be done in a separate thread so the main thread can keep pumping windows events and cancel the operation if the user chooses. The fifo files also break any multi file synchronization in progress. Because of this, I have to manually deselect a bunch every fifo file when synchronizing my folders.