I have had several long flights when the Xbee 2.4GHz S2 communication stopped around 30minutes after power up. This may be something to do with ubunutu/netbook settings instead of the Xbees.
I couldn't find anything in the forum on this. Please let me know if this is a known Xbee problem.
I do not use the Xbees so I don't have any details, but I know it hasbeen discussed at great length here and at rcgroups.
Did you have a screensaver or something else?
How is configured your netbook about the power saving ( stopping HDD or USB) when the netbook is in idle mode?
Have used XBee Pro 900 and XBP 2.5GHz modems without issues on long flights... Also have not seen any info on dropouts after 30 mins??