Allegedly some UNDI stacks don't cope well with interrupts.  This patch pretty 
much turns the world into a polling world.  This is relatively hideous, but a 
fairly short lifetime.

diff -urN ipxe-xnbaclass/src/arch/i386/drivers/net/undinet.c ipxe-undinetchange/src/arch/i386/drivers/net/undinet.c
--- ipxe-xnbaclass/src/arch/i386/drivers/net/undinet.c	2010-11-11 14:09:48.042334268 -0500
+++ ipxe-undinetchange/src/arch/i386/drivers/net/undinet.c	2010-11-12 10:37:01.332334042 -0500
@@ -258,7 +258,7 @@
 							   "nop\n\t"
 							   "nop\n\t"
 							   "cli\n\t" ) : : );
-			return;
+			//return;
 		}
 
 		/* Start ISR processing */