internet connection problem(bits stop)

I have pIII with 550Mhz,128MB ram,20GB hard disk and op system is win98(second edition).
This is my server with 7 client computer.I have dialup internet connection through 56kbps D-link modem,and distributing amang the other pc’s through proxcy software. internet is easily logged but transmitting and reciving bits are not indicating the movement of data and could not brousing.
but when i restart the server the problem
does not exist and this happens regulary
at a frequency of 3 to 4 times in a day.
please give me the solution as early as possible