NETWORK CONNECTIVITY PROBLEM

I HAVE THREE COMPUTER THAT RUN WIN2K 0UT OF THE 20 OTHER COMPUTERS THAT RUN WIN2K ALSO. BUT ONLY ON THESE THREE COMPUTER I HAVE SPORADIC NETWORK CONNECTIONS TO THE OTHER COMPUTERS ON THE NETWORK.
I CANNOT ACCESS SHARES OR SQL DATA BASE ON DIFFRENT COMPUTERS. ANY HELP OR IDEAS WOULD BE GREAT.