helping you would be easier if you can post the code from the script you are using.
Theoretically it would be possible to have a user with insert and update permissions and without a select permission
I posted the solution last night but it's worth reposting.
After some reading on the mysql boards I realized several people were having the same issue. All were using active perl and all were using the mysqlPP driver. I switched to using the mysql driver and the issue vanished.