First, I have to say that I have been set up an ad hoc wireless network at home to share internet connection between desktop computer and a laptop and it seems working fine except one disturbing thing - internet connection cannot be established when guest computer (in this case it is a laptop) shuts down or disconnects from the internet and then again connects to it, when host computer is powered constantly without restarting. To get internet working on laptop I have to restart my desktop computer as well. This applies only to internet browser on the laptop, everything else works fine (utorrent receives and sends information to the internet).
Second, This problem is only when desktop computer runs windows xp (laptop has only windows xp installed on it), when I use linux on my desktop computer, the laptop can be turned off and then turned on, the browser still get connected to internet. This is annoying, because my sister uses laptop and I have to restart the desktop computer often so she could serf on the internet.
I think there is no problem with hardware, because it the establishment of the connection fails only when desktop computer runs windows xp, so probably this can be solved by changing software configuration in windows on host computer.
If someone knows how to solve this, please make a response. Thanks in advance.
Accidentally, I found a solution to this by myself
Simply had to delete Update for Windows XP (KB973687) [Install this update to prevent applications from sending too many HTTP requests while a well-known Document Type Definition (DTD) is included. After you install this item, you may have to restart your computer.] How to Uninstall: This software update can be removed via Add/Remove Programs in Control Panel.