I haven't had that problem myself, but it very well could be a limitation of the storage driver version you're on in NW. The latest version of 6.5 I run in VMware is SP5 (though I run SP7 everywhere else). I haven't had this issue, but I don't do a lot of rescans...so it may not help.
You might even want to try setting your Netware box so it's multipath aware. I think it's "Set multipath support=on" At least that might give you a window for the driver to attempt a reconnect.