Adobe Acrobat Connect Add-in 9.3 r139 has encountered a problem

can you expand on what you mean by "nothing happens"  does any 2nd window launch (connectAddin)?  is IE8's popup blocker on or any popup blocker?  is the other computer configured the same as the computer that does not work?

you dont state which windows or flash version (http://kb2.adobe.com/cps/155/tn_15507.html) is in use by the client or what your Adobe Connect version is or if the server is doing SSL.  if you are not sure what version you have, append version.txt to your connectserver url.

example http://myconnect.mydomain/version.txt

and how the client is connecting to your connect server,  is your server behind a firewall, is their client behind a firewall.  if they are behind a firewall is there company ports open for RTMP ports.

also I dont have a quick fix for you but some troubleshooting tips

you stated that they removed the ConnectAddin from the add/remove programs but you may also need to check to make sure it was removed

#connectaddin location, can remove the connectaddin folder, once you reinstall the new it will recreate the connectaddin folder

win7: C:\Users\{userid}\AppData\Roaming\Macromedia\Flash Player\www.macromedia.com\bin\connectaddin

winXP: C:\Documents and Settings\{userid}\Application Data\Macromedia\Flash Player\www.macromedia.com\bin\connectaddin

to test and capture log info from the connectaddin, must create the mms.cfg

Connectaddin log folder, the file name will start with connectaddin-{current_date_time}.log

win7: C:\Users\{userid}\Documents\

winXP: C:\Documents and Settings\{userid}\My Documents\

#for winXX

#c:\windows\system32\mms.cfg

SingleLogFile=0

PlayerLogging=1

flashlogging=true

have them send you the logs to review you may also need to review the connect debug.log around the same timeframe, are you seeing anything odd.

after the testing make sure you have them comment out the lines in the mms.cfg, otherwise it will create a new file everytime they access a connect meeting room.

you can append ?mode=xml to the meeting URL. this will give you some detailed info within the browser. like which application server they are connected to and other info.

you could have the user try accessing the meeting room without the connect add-in, the addin is only required for that person to share.   just add ?launcher=false to the end of the meeting url, this will force the meeting room to display within the browser and just use the flash player.