Thanks for the reply --
There's scores of servers in this environment but the one I am using as a control set is Windows 2008 R2 on an ESX 5.0 host with current VMWare Tools (for that host). The metrics exist within vCOPS -- I can see them and report on them over time so this is not the problem so much as the logic triggers to create an alert from this condition. Nothing special with how the server is partitioned either.
98% capacity and no alarms.
I only see such alarms for C drives on other systems and I noticed the C drive metrics display differently
It very much seems to me as if non-C drives are simply not being evaulated for anything at all and this is what I would like to change. 
Thanks.