DNS fails to resolve

Hello,

I installed WordPress and it worked… and then installed BuddyPress and it worked…. and was uploading some BuddyPress plugins when suddenly the site disappeared from my browser. I checked my DNS on the server for the site and the nameserves appeared to have been changed. I reset the nameservers to the correct once and the site came back… The next morning I woke up and the site was gone again(pings would not find the site)… about 4 hours later, the site appeared again… I went to install a plug in(I can’t remember the name but it was supposed to give a more enhanced “facebook like look”). I activated the plug in and my site disappeared again and it doesn’t ping… any ideas?

It’s now 25 minutes later and my site has reappeared and pings… any ideas? Is there some setting on my server that I need to set to keep the site from disappearing anytime I do something with plugins?

thanks,
David