5250 emulation locks up on XP

We have some long-time data entry users banging away at the same apps,
same screens they've been using for years.  Because the apps can be slow
they depend heavily on keyboard buffering, keying entries from forms in
anticipation of forthcoming screens.  We could probably take away their
monitors and they'd never notice.

Anyway, we recently upgraded some users to new PC's -- from three year
old hardware running Windows 2000 to brand new Windows XP machines.  The
users with new PC's are having frequent 5250 session lockups.  Input
Inhibited is highlighted, but the screen never frees up regardless of
keystrokes or mouse movements.  The only solution is to close the
emulation window and start over.  The problem follows the hardware --
we've swapped PC's from user to user and building to building.

What's really strange is that we've tried changing the emulation
software, but we're still seeing the same problem.  We went from
NetManage's previous acquisition, ViewNow, to their more recent
acquisition, the Rumba Web-to-Host emulator.

It may not even be an emulation or keyboard buffering problem.  We
haven't had much luck debugging it at a network level.

I spent a couple hours scanning the archives and didn't turn up
anything.  Has anyone seen anything like this?

James P. Damato
Manager - Systems Administration
Dollar General Corporation