Can anyone help!

I have an application which is running without problems, with the exception that from time to time users are thrown out of the system with the following error message

fatal error:Exception code=C0000005
Called from - baseform1.references1click line69 {g:\client\classes\bsa.vct}
Called from - baseform1.basebutton2click line9 {g:\forms\frmcasessheet\sct}
Called from - editform1.casessheetclick line5 {g:\forms\frmcasesdetails\sct}
ON....line0 - editform1.casessheetclick line5 {g:\forms\frmcasesdetails\sct}
go line 95 fax common procedures go prg

The system was developed in Visual Foxpro V6, service pack 3
on a windows NT, with each workstation using windows 98.

The problem appears when accessing a word 97 object from within foxpro
can anyone suggest why, a fix or workround