I have been having some weird happenings with Hyper-V on R2 which I thought I would share.

I did have a R2 installed but the licensing got messed up so I ended up reinstalling from scratch. I exported the 2 Hypers I had and then reinstalled. Now I have had issues with very slow logon and it hanging for ages when I try and wake the main server up, theres no errors in the event log except really helpful ones saying that the server hanged on logon.. when you click on the even more helpful link to technet it says theres no help.

Anyway the Server 2003 client works great on it.. perfect pings and logs on quickly. The Server 2008 (non R2) was a pain, when I left a ping going it would time out every minute or so for about 10 seconds then come back, whenever I attahced to it the thing hung all the time making it useless... its my AV server so it hasn't been dishing out data for a few days now.

I tried loads of stuff including making sure the latest version of the additions was on the client, checking the IP address etc and even swapped the Virtual adapter with the 2003 one and it still was playing up.

I found another PCI-X network card so threw that in and it seemed to fix it until I changed the IP address to what it was previosuly. (the new network card was DHCP).

For some reason the address I was using was causing it all, 192.168.100.9/23. I had checked DNS and DHCP and all seemed okay but there must be something it hates.

I am sure others will have figured this out earlier but I was stumped, not sure if it was because of the import or just a rogue DNS setting somewhere but it was very strange... a combination of NIC and IP.