>But I found solution to my problem (from a message on Stackoverflow). What I needed to do is following: Enable all button at design time. Then disable those that need to be disabled in jQuery (in script). This way the post back (or no post back) that I set up at design time work.

Glad you got it working - but it occurs to me that if neither button should ever initiate a postback then it would be better to use a simple HTML input control rather that asp:Button in the markup so that the problem doesn't arise. i.e:

<input type="button" id="button1" value="One" />