Safe? Debian 5 to Debian 6 Upgrade

[DarkSide]

I finally carried this out on my live box today!

1. Upgrade to 1.0.7 was fine as expected!
2. Upgrade to squeeze was fine as expected!
3. Apache2 died as expected!
4. My commands above succeeded as expected! Everything worked!
5. I then rebooted to test everything was okay.
6. Bad news, after a long time (about 1 hour) server would not respond to ping.
7. Hardware reboot initiated!
8. Server responded to ping, so did www and ftp (but they were SLOW)! Then it died again (for about 3-4 minutes) then it all responded again!
9. The story is a success, the lessons to be learnt I do not know.

If there are any logs which may help then please ask. I would like to see this project maximise its potential! :-)