For no reason at all, with no changes to the NW 6.5 SP5 with BM 3.8 SP4
server (I really mean NO changes at all)
proxy started sort of stalling.

Unload proxy, load proxy -cc & all comes back to life (for few minutes or an
hour and then starts stalling again)

Browser does not time out, it just sits there waiting
F5 sometimes refreshes & it gets the page

After careful testing it is not machine in question (tried on tens of them),
not the ISP (as direct connection works perfect)

It is definitely BM itself

Any idea anybody? I mean, how could it go wrong out of the blue?
Failing NIC in the server?