I'm having a very annoying internet issue with my Macbook Pro. The typical scenario goes like this: I attempt to browse to a website I don't visit very often and the browser just waits forever and nothing appears. The blank page will spin forever, sometimes successfully loading the title, often loading nothing. Occasionally if I wait a while the page will load (or at least the title will appear). If I turn off the laptop's wifi I often see a half-loaded page; turning the wifi back on again and refreshing is usually allows me to load the whole page in another second or three. Pages that I visit often, such as gmail or this site, load fine and update their content easily (they're probably caching nicely, I'm assuming). Sometimes the laptop surfs fairly well, without issue on any sites.
- No other computers (an iPhone, Win 8 box, and Win 7 laptop) have any internet issue.
- The problem laptop is running Mac OSX 10.7.5
- The ISP is Verizon fios 15/5 Mbps
- The problem occurs on both Safari and Chrome
- Occurs equally often over wireless and wired connection
- I have tried restarting the router and updating the OS (through conventional means at least)
- Pinging doesn't seem to be affected -- I can very consistently ping pages at reasonable speeds.
- movies streaming works fine, though the initial movie load is often problematic and requires a wifi restart half-way through.
- I tried taking it back to the store--they showed me how to delete some browser cache files but it didn't seem to help (I believe they deleted the contents of ~/Library/Caches and possibly another folder I don't recall). We were seeing strange ping performance in the store but I think it may have been them not me.
How can I diagnose the root problem (regarding strange internet connection issues that affect just one machine)? Bonus points if you can tell me how to fix my problem.