blockUI plugin problem : unexpected behaviour

blockUI plugin problem : unexpected behaviour

I have an urgent issue with blockUI.

When my page is first loaded I have different blocks to be loaded via ajax.
I have added the block and unblock in ajax start and stop as recommended in blockUI overview guide:
  1. $(document).ajaxStart($.blockUI).ajaxStop($.unblockUI);
but the problem is that after the first pages are loaded, nothing works then;
so the first conents are loaded and the block is shown properly,
but after that all my ajax links don't work at all

what is strange that if I add just a simple alert with the block part like
  1. $(document).ajaxStart(function() {$.blockUI();alert('hello');}).ajaxStop($.unblockUI);
with this it works fine

have someone experienced such a problem?

it's very urgent, please help.

Thank you in advance,
Aram