Default properties changed !! mysteriously during operation

Hi All

I have been developing an application which depending on
certain logical "if ,then, end if" statements either opens
datasheets as read only or edit.

However, from time to time, the default settings for the
data sheet forms get set to "no edits", "no additions" and
the statement " acEdit" , which I decided to use after a
few incidents

docmd.openform acForm,formname,,,acEdit

does not appear to resolve the issue for those times the
form should allow editing. I am totally bewildered, any
help would be most welcome

Cheers

Dotun