2.0: cannot connect to database after using Database Explorer in VS

[RAM]

Hi,
(Sorry for my English...)
I have such problem: if I use Database Explorer in Visual Studio I will not
be able to connect from my application to the database; when I don't use
Database Explorer there's no such problem. (I have checked running
processes: I can see dexplore.exe - is it database explorer?)
Please help to solve the problem. Thank you very much!
/RAM/