I've just about finished transferring must of the old Virtual server images to Hyper-V on some of them, the Network card was lost with the "Virtual machine Bus" not being updated in Device Manager. Effectively it had not somehow skipped HAL detection when Integration Services Installed.
1. run msconfig
2. go into Advanced Boot options
3. Click Detect HAL
Everything came up on reboot and NIC went from 100MBit to 10Gbit 😉
Quick rant. WTF was the Hyper-V team thinking calling the additions "Integration Services". This has been a SQL product since 2005, causes much confusion when a SQL dude is tole to install "Integration services".