First thing I would investigate is getting the CSP - Concluding Service Pack for Technology Level 5.
Note that AIX 5.3 is currently at TL08 SP3, and the TL5 CSP is over 12 months old.
For a graphical view, as well as the place to get the update try: http://www-933.ibm.com/eserver/support/fixes/fixcentral/pfixpacks/53 (http://www-933.ibm.com/eserver/support/fixes/fixcentral/pfixpacks/53)
IBM Help Desk would probably say go to the latest, but I would check with your application support first - and also prepare an alturnate disk install (clone and update to latest AIX level) to see what gives me the best results.
Lastly: your specific error:
michael@x054:[/usr/include]grep 73 errno.h
#define ECONNRESET 73 /* Connection reset by peer */
michael@x054:[/usr/include]From this I suspect you need to be looking at network connections and why they might be resetting. By peer implies it the 'other side', so it may be something on the client side. Discuss this with eXceed, and/or have the eXceed diag tools running whewn you connect - and 'hope' you get the error message so you can see both sides of the diagnostics.
If the connection gets closed - it does not surprise me that async communications are not occuring as expected. (and considering this makes me wonder whether the X client has anything to do with it. Maybe there are too many async streams open?
Do keep us posted on progress, or lack of progress
