Sorry for this late answer...

So, I said "brownout - no" because the circuit is working fine if there is no power component connected (220V). I did not specified, but the power components are commanded through 12V relays. The relays are taking around 12mA each, and the worse case is 9 relays powered at the same time. Even with all relays powered, which is a hypotetical situation, the circuit is working fine.

To command the relays, I'm using serial latches UCN5841. Maybe there are other better solutions, but this was an imposed solution (the company has bought a lot of this chips for a previous project, with a very good price). I did not see any inconvenience to use such latches. This goes to Alberto's question: I'm not using any optocoupler.

Even if I know the importance of a watchdog, I'm not using now such thing. This is a prototype project. The next version will include for sure a watchdog. Anyway, a restart in the middle of the operation will not make me happy. Except the power failure case, which can put the whole system in an unknown state, I can manage this with few jumps, in the program, at the start routine.

As a temporary conclusion, after reading what all of you pointed to me, I'll try points 4,9,10 and 11 from Erik's list, (http://www.8052.com/faq.phtml?FAQ=84), the rest being already done or not aplicable.

I'll come back with the results. Thank you all.