How to disable a Button in APS.Net

How to disable a Button in APS.Net

I have big problems with disabling a Button in APS.NET. When i disable the
button on client side, the button is enabled after postback. When i
disable the button on server side, i can't save a mask because the button
is away.
How can i fix that? The saving action is executed on the first
Preload/PostBack. Meaning that the second PostBack and everything after
shoud not do the save process.
Also my Button is created new after every preload. How can i give this
Button a fixed ID so that it is always the same object that i'm
overwriting and on witch i have acess.