There is an IP conflict with another PC

Hello,

i get this message "there is an IP coflict with another PC in your network" or somthing like that. I found out that it must be about somthing like " port 135 in windows registery" which i should turn off. is that true, if it is what is that " port135" and what does it do? what will happen if i turn it off?
since i dont know how to work with windows registery, can anyone tell me how to turn it off? or give me a link?

if it's not about that port, what should i do? or if it's too complicated to be explained here, is there any other way??

I use Wix XP SP3. ( by the way I have an ADSL 512KB connection if it's needed for your answers)

thank a lot