asus p552w - notify icon

[code79]

Hi all,
a few time ago i've bought asus p552w and i've just a problem:
when i receive a new sms or a new call (without answer) i see both notify icon on the start bar for 30 minutes about..After that time, the notify icons disappear..

Is it a bug? Or some device setting?

The Asus customer service desk has suggested to reset my smartphone to factory settings and i'va done that, but the problem is the same..

help me please...

Thank a lot..