DTUs freezing randomly in XP VDI sessions

Question

Software:
VDI 3.2 (upgraded from 3.1) on three Solaris 10 10/09 x64 servers in the recommended HA bundled MySQL config (primary, first secondary, second secondary)
Desktop provider is VSphere 4.0.
This issue primarily affects a VDI pool of ~65 Windows XP 32-bit desktops.
Any affected desktops already have the Oracle VDI Tools and SunRay Windows Components which were bundled with VDI 3.2.
Hardware:
Sun Ray 2 and 2FS models, upgraded with the firmware provided with the VDI 3.2 release (GUI4.2_140993-03_2010.06.21.19.00)
Smartcards are mandated for hardware Sun Rays.
In the last month or so, we have started seeing more and more random "freezing" of sessions whilst users are already logged in and working - users are typically just using Office, Firefox, Thunderbird etc. - nothing complicated!
Essentially, their screen will randomly freeze completely and the mouse pointer cannot be moved. The only way to fix it is to remove the card or kill the session with CTRL-ALT-DEL-DEL-Bkspc-Bkspc.
Upon doing so, the session comes back to life immediately and they can continue working.
Here is a portion from /var/opt/SUNWut/log/messages which is produced at the moment the session freezes on the server that happens to be hosting the session (I've changed the server hostname, username and domain name for security reasons):
Dec 14 10:56:57 vdiserver utauthd: [ID 794400 user.info] SessionManager0 NOTICE: EMPTY: ACTIVE session
Dec 14 10:56:57 vdiserver Sun Ray Connector proxy:[21218]: [ID 855542 user.error] Child closed socket prematurely, session shutdown
Dec 14 10:56:57 vdiserver kiosk:vda[22715]: [ID 702911 user.error] /opt/SUNWuttsc/bin/uttsc exited with error code 141 - exiting
Dec 14 10:56:58 vdiserver kioskcritd[20958]: [ID 422571 user.info] Info: a critical application has exited.
Dec 14 10:56:58 vdiserver kioskcritd[20958]: [ID 342793 user.info] Terminating Kiosk Primary Session ( pid=21106 )
Dec 14 10:56:58 vdiserver kioskcritd[20958]: [ID 308018 user.info] kioskcritd stopped
Dec 14 10:57:04 vdiserver dtlogin[22800]: [ID 118685 user.info] pam_sunray_amgh::[DPY=6] AMGH_SUMMARY: token=user.1290677160-1567, username=, AMGH_Done?=NO(Local Session), Details=AMGH is not configured., AMGH_Target=*NONE*
Dec 14 10:57:04 vdiserver dtlogin[22800]: [ID 976841 user.info] pam_kiosk: pam_sm_authenticate: Initiating Kiosk session with user utku35
Dec 14 10:57:05 vdiserver kioskcritd[22946]: [ID 190395 user.info] kioskcritd started
Dec 14 10:57:10 vdiserver cacao:default[26773]: [ID 702911 daemon.warning] com.sun.vda.service.client.ClientRequestWorker.run : Failed executing vda-client request: serverList([email protected], token=user.1290677160-1567
, clientAddress=127.0.0.1): No preferred servers found for [email protected][ExitCode=15]
Can anyone offer any help? I know about the "no preferred servers found" error, which I think is produced since we're not using the "Global VDI Center" feature - correct?
The main issue certainly looks to be caused by uttsc, which is simply crashing...
Any ideas?

Answer 1

@turbotiga - thanks a lot for all this info. Really helpful.
A few questions/comments:
a) Is this information about which patches are already (or not) applied to the full VDI releases published anywhere? I can't see mention of it on any of the wikis - how have you discovered this? It would be great to know this detailed info - for future releases too - e.g. what patches are already rolled into in the SRSS/SRWC components included with VDI 3.1, 3.2, 3.2.1, and which have not been and why? EDIT: Just noticed that the release notes mention that VDI 3.2 includes "SRS 5 Patch 3", whilst 3.2.1 includes "SRS 5 Patch 5" - guess that explains that....
b)Our suppliers (who also initially installed the systems) had recommended that the versions of SRSS and SRWC etc. that are bundled with the complete VDI packages are included for a reason at that very specific patch level to provide the best matches/compatibility, and that we shouldn't ordinarily install patches for other versions of SRSS etc. against the VDI installation as a whole (I guess unless otherwise instructed to do so from Oracle/Sun). That is why I had assumed that upgrading to 3.2.1 would be a better solution (albeit it will involve considerable downtime compared to patching individual components since it involves taking down the database and rebooting etc.)
The patches now only seem to be available from the My Oracle Support site (which requires a contract number to access) so it's a moot point anyway since we don't have the rights to get at them any more...are they available from anywhere else?
I would be very happy to give the installation of patches a go rather than upgrading fully to 3.2.1 in the first instance purely since we can't afford the amount of downtime that a full VDI upgrade produces right at the minute...is it definitely safe to patch our 3.2 installation with later SRSS/SWRC patches (against the recommendations of our suppliers) rather than going the whole hog and upgrading to 3.2.1?
Edited by: Hutch on 20-Dec-2010 06:03