+1 to what Don and Ian said, especially Ian's reference to my web site. ;-)
Having the PO attend has upsides and downsides, but does not really violate Scrum either way. "Solving issues" is sometimes an ok thing to do in the Daily Scrum, sometimes not -- depends on the team and whether the team is able to solve issues, have the PO present, inspect and adapt the plan via yesterday/today/obstacles, and sill meet the 15 minute time-box. I've seen it happen, but not usually with beginner teams.
For more info on this, see the following patterns on my Daily Scrum pattern overview page:
Product Owner Attends
The After Party
Defer Obstacle Resolution
Allow Obstacle Resolution
Overview page here: http://www.scrumcrazy.com/Overview+...m+Patterns