ESXi 4.1 on IBM metal with vCenter on a Server08 R2/SQLEE VM hosted on one of the hosts.
My vcenter --> host --> performance --> overview --> network chart show 0kbps constantly. If I go into the Advanced mode, I see traffic on the NIC's.
The same is true with the Memory (MBps) chart. The other charts all have data.
I saw a post talking about altering the vcenter db to change the field type on some history tables and recreating a couple of views - I did that and have waited a day with no changes in those 2 charts.