If so, then you may have a failing wireless adapter.. Of course, I'm assuming when you say the "icon" is disappearing that the wireless connection is also gone at that time.. ?? In such cases here, when an old computer is involved, we purchase a new, external USB wireless adapter, disable the old one and enable the new one.
Hope this helps.
I'm using Lenovo 3000 N100 laptop. For the last 1 week, "Wireless Network Connection" icon disappears in my laptop and if I restart after 4-5 hours it again comes. I have another computer connected with the same network, and that works well. My laptop's drivers are updated.
OS: Windows XP,