I believe I have experienced this problem frequently myself, and:
a) The problem being described is (I believe) a data base issue whereby (I think) that the host Mac iTunes makes some small routine record changes to the iTunes database (/Users/username/Music/iTunes/iTunes Library) on start-up, and, when/if the guest Windows iTunes when started 'notices' the change, so Windows iTunes checks/rebuilds (i.e. updates) the iTunes library and in so doing makes makes some 'small routine changes'.
Then (and you have guessed this!) when the host iTunes starts up, it finds a change it 'updates the iTunes library' again and so on so and so on such that they never finally stabilise.
b) My guess is that you computer does not freeze so much as, take inordinate amounts of time to update (can be hours - especially on the Windows iTunes - which is functionally the same as freezing in practice)?
c) Since my network is fully functional (and bridged makes no difference), I believe that tinkering with the network settings will make little or no difference.
d) I believe that the solution will emerge as either:
1) A significant update to iTunes that stops this pointless 'fighting' between two iTunes applications attempting to share a single data base
or
2) Setting up a different library for the Windows library to the Mac library. Please note: This CANNOT be achieved via the iTunes Preferences settings for either the Mac or the Windows iTunes applications, iTunes 'appears to' search for and successfully find the Library if it is anywhere on a directory that is shared by the Host and the Guest.
So: If anyone knows how to resolve this fighting between iTunes (i.e. Mac vs Windows) AND MAINTAIN SHARING of the .mp3 files within the data library, I would be VERY interested.