I came across an issue today with a Dell 2900. Every time I rescanned the host bus adapters I got a Purple Screen Of Death. After some research on the issue, it appears that it is a known one and will be resolved in a future bux fix from VMware.

The issue is with how the ESX kernel handles the USB controller in the Dell 2900. VMware engineering is working on the patch and the current workaround is :

Edit the /etc/modules.conf and remove the entries for USB as listed below :

alias usb-controller usb-uhci
alias usb-controller ehci-hcd

I can confirm this workaround does indeed fix the problem