CA Express and multiple 5250 sessions

Hi, I'm having problems with CAExpress V4R5. Have many PC's installed
same version, same ServicePack (latest). OS/400 also V4R5 and latest Cum
level.

Some of them have no problem to configure two or more 5250 emulation
sessions...
Some others, just CANNOT.
Well you can always try to configure a second session, but when it comes
to try to connect, you get an error about "licenses in this PC"...
If you "disconnect" the first session, then second session will connect
ok without changes, but then the first session will get same error if
you try to reconnect it with the second one still active.
The error in each case was CWBLM0011, saying something about licenses
"in this PC"... but at the same time other PC's can have 2 or 3
simultaneous sessions...
Digging in a little deeper, in CAExpress log, I see there's a previous
message (CWBSY1003  ? sorry, I don't have on hand) that just mentions
"invalid SystemName" but that is NOT probably the real reason, since
just disconnecting the other (first) session then the second one
connects without changes... No problem then.

Searching thru the archives I only found Rob Berendt's thread about
"Upgrade to V5R1 issues:" but here he just mentioned "Have all PC's
reboot.  Some people just log off.  Failure to reboot may result in PC's
receiving a CWBLM0011 error when trying to start more than one 5250
session." as something maybe related to V5R1, and rebooting, and in our
case has nothing to do with V5R1 (we are at V4R5), nor with rebooting...
(we've tried all different types of combinations, reboot  PC, reboot
AS/400...) and it's just some of the PC's (always the same ones) that
suffer this disease, but not the others!

Any ideas?
TIA, Antonio
-------------------------
Antonio Fernandez-Vicenti
afvaiv@wanadoo.es