IIRC, when an Access db is opened, the default mode is read-only. SELECT will work fine, but any attempt to modify the data will fail, regardless of user permissions. There are optional flags that can be set while creating the connection which override the defaults, though I don't remember where they're defined at the moment. Try MSDN - I was working with ADO when I bumped into this, so that might be a good section to start searching. Boredom, Bull$^%&, Baggage, Bar - all start with 'B'
Coincidence?