How to block the system standby process?

hi all:

I am currently developing a IM client. The client should send a logoff
message to the IM server while the windows system stand by. And the client
should auto reconnect to server once the system restored.

I know that there has a windows message tell the windows form that the
system is gona to standby.I can get the windows message but I want to make
sure that my code will be excuted once the system gona to shutdown. Notice:
the logoff process is asynchronous.

So I had the following choice:
1. I can block the standby process and wait until the logoff signal. But
we must make sure there gona have a time out.
2. I should try another method.

So what's your suggestions? Thank you in advance.

And by the way. How to block the standby proccess?

jianglinchun
http://www.fetion.com.cn