When I wrote about using ipconfig /flushdns to fix intermittent Internet problems, a longtime reader reported he has the problem frequently on his dialup connection. If you find yourself doing this a lot, there’s a more permanent fix.
Go to Start, Run, and type services.msc. Scroll down to DNS Client, right-click, and select Stop. Then right-click and select Properties. Set startup type to Disabled and click OK.
This keeps Windows from caching DNS queries entirely. Normally the caching speeds things up and is a good thing–that’s why all versions since Windows 2000 do it–but if you find yourself running ipconfig /flushdns all the time to keep things working, disabling this service will give you a permanent fix.
To temporarily disable it, you can just stop the service and start it again when finished. If the problem typically occurs at certain parts of the day, that could help provide some relief.