I just spent a long time with Tivoli on the phone with this exact same
issue.  We have determined that it is a bandwidth issue.

Some of the things we are currently testing are juggling schedules.  Turning
on Compression.  And installing a gigabit card in keys systems.

The best so far has been the juggling of schedules.  It is tough.

Or of course spend money install switches, segment more, by better hardware
you know, money solves all right.