"Cannot locate the Internet server or proxy server." is caused by too many things. What's in the discussion is not enough and not deep enough.
You must tackle areas such as:
1. Spyware.
Today's pests are hijacking the DNS, the TCPIP stack, inserting proxies and more.
2. The DNS poison issue.
This issue seems to be fading (thankfully!) But another member and even I have run into this one where the ISP's DNS (server) was being attacked and the result was ... the error message above. Untold hours have been spent on this one, but I pull the plug fast since I can ...
3. Use NSLOOKUP to see what the DNS is doing and possibly failing.
In closing, you may learn more than you need to about how the internet and web browsers work. You may have an issue with the PC, the OS or your ISP. But there is far too little detail to point to any specific course or action.
Bob
Bob,
If you spare a couple of minutes take a peek at this short thread where I am involved and, if you don't mind, let me know your opinion of this MS MVP Ben Schorr.
Thanks.
http://www.microsoft.com/office/community/en-us/default.mspx?dg=microsoft.public.onenote&mid=796b4c4a-2dbd-4c35-8d3c-316b4593a097
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