Found the topic with the simiral issues described:
http://fm.en.kupaisky.com/Community/Forum/View.aspx?num=28323&pagecount=0&page1=2&searchtype=0&category=C01&searchvalue=&sort=5
- disconnect message (every time)
- notifiation about hacking attempt (some times).
- issue reproduced after special XP patch installation
Whereas that topic was closed by unknown reason, so left this opened.