I've encountered this problem before and I believe it may affect other drivers (I could test but I don't have time). This was happening on my custom Linux system with the pcnet32 driver.
pcnet32: eth0: transmit timed out, status 97fb, resetting (and some other kernel module tracing in dmesg)
Basically it means the card is connected (it shows connected in full duplex etc.. and recognized if the cable is disconnected too) but no packets can be sent or received........
You'll see the following and the boot process will freeze:
io scheduler noop registered
io scheduler anticipatory registered
io scheduler deadline registered
io scheduler cfq registered (default)
I have struggled with this issue on vari........
NET: Registered protocol family 2
The above is the last thing that I ever saw, I tried pci=routeirq etc.. and it wouldn't work.
The solution is to enable IOAPIC in the VBOX Settings
Just enable "IOAPIC" in the settings for your Centos Guest and you'll find the kernel boots just fine. I wonder if a physical system might stall in this same way if the BIOS has IOAPIC disabled which many people do as a troubleshooting method.