WebTools Synch error (HRESULT: 0xFFFFFB9E)

This is a ramp up installation with SBO 2007 PL3 and WebTools 2007 (Synch version 2007.0.622). The synch is set to 20 minutes and it seems to run fine for a while but eventually it gets the following error after the "Loading Business Partner Queue" message.

<messagetype>E</messagetype>

<date>2007-09-11 12:38:32.53</date>

<synchmodule>Synch</synchmodule>

<message>Exception from HRESULT: 0xFFFFFB9E

at SAPbobsCOM.CompanyClass.GetBusinessObject(BoObjectTypes Object)

at NetPoint.SynchSBO.SBOObjects.SBOPartner..ctor(Company company, SecurityTicket st)

at NetPoint.SynchSBO.Synch.LoadQueues()

at NetPoint.SynchSBO.Synch.SynchAll()</message>

<synchmethod>SynchAll()</synchmethod>

<objecttype />

<objectid />

To fix the problem I just stop and restart the service but this error prevents anything else from synching. The synch ran fine for over a day previously before this error started occurring again.

Any ideas anyone?

Steve