An exit relay that has just been updated to 0.2.4.17-rc produced this
message
Sep 07 19:59:30.996 [Warning] Your Guard maisterikaarna
($C3B7CC79FD4E302AF8956A7B02F0FC7AAB4A6AF8) is failing a very large
amount of circuits. Most likely this means the Tor network is
overloaded, but it could also mean an attack against you or
potentially the guard itself. Success counts are 52/151. Use counts
are 0/0. 52 circuits completed, 0 were unusable, 0 collapsed, and 1
timed out. For reference, your timeout cutoff is 142 seconds.