I agree with many of the suggestions made by dgraab re dealing with the issue of your daughter's acting out.  Speaking to the teacher, evaluating the effectiveness of the consequences being employed for both negative and positive behaviors, and examining her routine at home are all solid ideas that have potential for helping with this problem.  
 
I would add a couple of thoughts for you to consider.  First, it might be helpful to ask the teachers and staff who work with your daughter to do a little simple research for a week or two or three.  See if they are willing to notice what the antecedent conditions are to the acting out.  In other words, what happens before she starts the negative behaviors? During what activities is she appearing bored?
 
Is the boredom being verbalized, or is there some non verbal behavior that the teachers are labeling as "bored?"  Identifying the conditions that precede a behavior can lead to strategies that might help extinguish it.
 
Another thought is this. What appears as "bored" can be the outward appearance of an inner emotional or psychological dilemma.  You describe your daughter as "smart" and "bright." Why not sit down with her at a quiet time when you can give her your undivided attention, and ask her what is causing her to "bug" the other kids? Six year olds can say a good deal. It may not always be direct, but if you listen carefully, you will get clues and ideas about cause and correction.
 
There are experts in the child behavior field who recommend collaborating with the child on a solution.  You can gently tell her that "This behavior has become a problem in your class.  What do you think would be a better choice. What can you  do to make a better choice?"
 
Avoid shaming and blaming.  Look at choices, consequences and solutions. If you have received information from the teachers about the antecedent conditions to the acting out, you can have a conversation with your daughter that is specific to  what sets the behavior in motion. You will probably need to have more than one conversation with your daughter. This is to be expected.  Also, the collaborative approach is not  designed to be used instead of the other suggestions, but rather in tandem with them.
 
For example, if your daughter can think of a better choice to use in class when one of the antecedent situations (that can be revealed by the teachers' "research")  happens, you can encourage her to use that choice behavior instead of the one that is problematic. You can talk about how she is going to remind herself to use the new behavior. You can give her positive reinforcement for her efforts when she begins to use replacement behaviors.  Remember, specific comment on achievement is more reinforcing than general praise.  Your positive attention can also be a great reinforcer.  
 
If your efforts fail to begin yielding results in a month or two, or if the behavior worsens, consider psychological testing. The school will probably be able to make a recommendation. However, from what you have said, it sounds like your child is capable of making better choices, and does do that some of the time.  This leads to the conclusion that the negative/interfering behaviors are in fact choices that she can control. With adult support, guidance and encouragement she can learn to make better choices that will lead to school success and positive self-regard.
 
Bette J. Freedson, LICSW, LCSW, CGP
Clinical Social Worker
JustAsk Expert
http://www.singlemomsos.com/index.html