User Defined Filters ???

Every so often, my User Defined Filters get populated with these filters:

Critical_10   
Has Finish Constraint   
Has Start Constraint   
Level of Effort_1  
Level of Effort_3   
Level of Effort_6   
Milestone   
Negative Float   
Non-critical   
Normal   

After deleting, they will show up every so often. Any ideas how to permanently stop them from showing up in my User Defined list?

Thanks for looking,

CAM