I'm using the software usage features of ZCM 10.0.3

For all of my managed devices (about 50), on the software usage tab i have strange results :

For exemple, for one device, i have 46 hrs used for IE and 25 hrs Active.
And for the OS, Windows Xp Pro i have 79 hrs used and 0 on hrs Active, it should at least 25.

See attached image (soft.jpg)

I have the same results for all of my devices (Clients are 10.0.3)

Does anybody has same sort of result ?
Or is it normal, the agent does not track the OS ?

Thanks for your responses
and sorry for approximative english ;-)