Vista - Windows Vista Performance Monitor Alerts

Hi,
I have a problem with Performance and Reliability Monitor into Windows Vista.
I created a Data Collector Set with an agent (alert type) with Free Disk
Space (megabytes) counter that should fire when it will be less than 80GB (so
I put 80000).
I also set the checkbox to write an entry into event viewer application log
and also it should run a task (a batch file that create a simple *.txt file).
I started manually the data collector set (no shedule defined because it
should be always running), but it doesn't work: it doesn't write anything
into application log and I think it doesn't run the batch file because I'm
unable to see the *.txt file.
The user who runs the data collector set is SYSTEM (but I also tried with my
user that is into local administrators group).

Please, help me.

Thank you a lot.