The regeneration timer seems to get out of sync with the server a lot very quickly. The deviation can be up to 5 minutes between two regenerations (10 minute period) on my system and varies with CPU load. I assume you use some internal tick timer. You should use some absolute time source like system time or sync with the game server.
Gentoo Linux, Adobe flash player 9.0.124, Intel Core Duo T2600 (1.66GHz).