I used the word Vista and your subject and it appears that this has open discussions like http://www.vistax64.com/vista-performance-maintenance/65977-reliability-monitor-no-longer-adding-new-data.html
If that doesn't apply google that again and see what else folk are saying.
Bob
Even though in the "task scheduler" rac agent is enabled my "reliability monitor" has not updated since 11/30/2010.I have not made any changes and my system is functioning fine otherwise.OS Vista home premium

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