This post shows my problem exactly, except it's not happening on SAM, but on virtual hosts that are being polled via 32bit NPM pollers
http://thwack.solarwinds.com/message/214085#214085
I believe what is required is the ability to switch NPM to use a 64 bit poller instead.
Some of my virtual hosts have 80+ logical CPUs and all of them have this annoying error spamming the event logs.
My servers are being polled via WMI in order to poll the Hyper-V information as well