Hmm, nasty.
Fortunately Wyse are quite good at resolving these however you will need to give them a dump of the error.
In the WTOS parameters guide is the procedure for creating a dump of the session. This allows you to “record” the session and support can play back the error and debug.
If you have not been asked to already maybe supply support with one of these captures,
Cheers,
-TT