I've been running my WSPR station on a new Ubuntu Desktop 10.10 install on an MSI laptop and for mysterious reasons hadn't been spotting anyone or being spotted. I could see strong traces though.
Happily, this is now fixed quite markedly:
My thanks go out to Nick, VK2DX who wrote to point out that my clock was off.
It turns out that this Ubuntu install does not include the NTP daemon.
I think this may cause problems for other software as well.