I was having problems with the map down-loader where it would freeze up even after i downloaded all the main maps...and the only arena i could join was early war...i saw this post and double checked my firewall and antispyware even though i didnt have a problem before hand and emailed support and this is the reply that helped me and may help others as well....
"There is a bug in the terrain downloader where if you cancel it or resuem it, it will hang. Once this happens, you have to clear out the "temp" folder in the Aces High installation directory in order for the downloads to resume."
-Roy
Thanks for your help Airlynx