Home sharing crash itunes 10.5.0.142 on win7 pro service pack 1 64-bit

Question

8 GByte RAM, Intel i7 CPU, flash hard drive (256 GB) with files stored on Ethernet shared file server (2 TB)
per bottom of iTunes window:
16-17k podcasts, 354 GB
9800 songs, 80 GB
34 movies, 110 GB
17 tv shows, 114 GB
5 iTunes U, 0.9 GB
26 books, 5.2 GB
14 apps
iTunes runs until I try to view a (DSL-downloaded) TV show. The wifi apple tv stops playing a minute in, give or take. The apple tv also stops listing the computer in the top-level user interface.
iTunes on the PC crashed.
There was a while where home sharing didn't work. Then it worked (fixed in a software update or apple infrastructure, as other postings indicate). Now, with the most recent update, it looks like a bug has been introduced into iTunes.

Answer 1

Home sharing no longer crashes, but it also does not work:
google searches provide example lore, such as found in apple's own:
http://support.apple.com/kb/TS2972
set up home sharing on devices; toggle home sharing off/on on devices
No, this is not a fix. Neither makes progress.
use latest software on all devices (iTouch, two apple tvs, win7 itunes)
No, this is not a fix. All devices are up to the latest software.
As an example, 4.4.2 (3160) didn't work, and neither did 4.4.3 (3323) for the apple tvs.
Check apple id used
No, this is not a fix. All devices use the same apple id, tested by viewing items and by purchasing items in the store.
Check your network.
Home sharing used to work. Nevertheless, transitioned from wifi-based apple tv and Ethernet star network off home router to: Ethernet based apple tv; Ethernet switched connectivity via Linksys 5-port GbE switches, with home router only needed for wifi hop or DSL to Internet. No improvement. Also transitioned from DHCP to static IP addresses. No improvement. This layer-2 focus avoids issues such as layer-3 IP TTL values for multicast, were the home router to switch at layer-3 rather than layer-2 among local devices (note that it all worked with original flows through home router, so this is just proof of expected FUD). All cables are CAT6, not 10/100 cat5, nor simply cat5e.
Check firewall settings
disabling the firewall does nothing (win7, all cases, home or work and public network cases)
Neither does the more-detailed manipulation of rules for inbound and outbound traffic for TCP (3689) and UDP (5353) when the firewall is enabled. (Disabling the firewall is clearer proof that the rules are not the issue.) Bonjour (mDNS) should get through just fine.
Quit and re-open apps
Not a fix
Power cycling
Not a fix. All gear has been power cycled (apple tvs, laptop with itunes, router, etc).
iTouch browsing
settings/wifi = on
remote app / home sharing = on
both apple tv libraries are discovered (one is Ethernet-based; one is wifi-based)
The laptop's is not listed.
authorize/deauthorize laptop
Not a help.
restart bonjour service on windows laptop
Not a help.
restart itunes on win7 laptop
Not a help
run latest win7 64-bit wireshark on laptop while running itunes
looked a bit silent wrt the laptop's itunes
control panel / add/remove programs / bonjour (10/15/2011) / repair
This showed the use of 224.0.0.251 UDP packets for bonjour. However, it did not persist.
I suspect a bonjour service - local iTunes issue. Perhaps iTunes has to interact with the service in order for the service to participate in the wire protocol. The iTunes UI is OK, so it is some internal detail.
In the past I have noticed that a heavy download load by iTunes inhibited home sharing. It may be a threading issue within iTunes.
Summary: still not working.