I don't think the problem is with AirDroid, I think the problem is caused by Android, as stated by
PBX_g33k
I used the procedure given in the following blog post to get AirDroid working again after the error message was displayed:
http://fitzcarraldoblog.wordpress.com/2012/10/25/airdroid-a-handy-android-app-for-managing-your-phone-from-linux/