Valentina Xtra Error - Appears After 10 Mins???!!

[Bub]

Hi,
 
I'm creating a CD-ROM with Director that is using the Valentina Xtra.
Everything runs successfully and repeatedly.... for about 10 minutes! If I
don't use the application for a while in Director, restarting it produces
the error:
 
-- "Script runtime error Integer expected script"
 
Which is complaining about the following line of code:
 
fldRef = addField(gPostcodes, demoRef, "postcode", #kTypeString, 10)
 
Once again, this works fine when the application is initially run.
 
I have the following code in the stopMovie handler:

Flush(gSchool)
Flush(gPostcodes)
CloseDataBase(gSchool)
CloseDataBase(gPostcodes)
ValentinaShutDown

Any idea what might be causing this annoying error!

cheers,

bub.