Access Issue In In 2005

I have some software that connects to SQL Server using Integrated Security in my connection string. My users are members of an active directory group. In SQL Server 2005, I've added the AD group to Logins, checked the User Mapping for the database, and checked role memberships db_datareader, db_datawriter and public.

When I look at Properties->Permissions of the database, the AD group is listed under Users or roles. I checked Connect, Execute, Select, Insert and Update are checked.

The users in the AD group still cannot access the data. 2 questions:

-Is there a log that will tell me why they're getting blocked?
-Is there a better way to give access to a new group of people?

Thanks!Brian