I have been using Ubuntu 10.10, and the major problem was the wifi, which was not working at all. It worked in Ubuntu 9.10. So after many futile attempts I decided run a Live CD of Ubuntu 9.10, and then wifi worked. Then after restarting I was amazed to see that the wifi was now working in ubuntu 10.10. What could be the reason? I tried lot of things, like blacklisting ath5k, but nothing worked out. Now after doing the Live CD, it's working.
Some hardware needs to be initialized before it can work. The initialization is good until the hardware is turned off, so you can boot to an OS with a fully working driver, then perform a warm reboot to a second OS with a partially-working driver, and use the device in the second OS.
Often the initialization consists of loading the proper firmware. What may have happened (I know the phenomenon exists but I don't know if your device is an example of it) is that the firmware was illegal to redistribute, and so was excluded from later Ubuntu releases, but is still present in 9.10 (either because you grabbed it before it went away or because no one cared to remove it from the earlier version). Of course, another possible explanation is a bug in the initialization code in the newer driver.
(Yet another hypothesis is buggy hardware that only works when it's hot enough… That's rare but possible.)