wanadoo trouble

[Immi666]

i use wanadoo anytime as my ISP and i'm havign trouble with it.  i log on fine and connect fine, for the first half an hour.  then i'm cut off.  i try to get back on and it tells me it is unable to make a connection/detect a dial tone.  i have to reboot the computer before i can reconnect.  this is extrememly annoying.  i have windows 2000 professional and 56k dialup modem.  dont understand whats going on.  is it my computer?  or is it wanadoo?  any ideas?