for the past few months I've not been able to use the sites www.google.com www.wikipedia.com www.youtube.com
on any web browser, Mozilla and IE being the most common that I use. No other site seems to be affected. I can view them through various proxy sites, but the reduction in speed is quite a problem, particularly with youtube.Whenever I do try to access these sites I receive a Failed connection message saying (among other things) "Though the site seems valid, the browser was unable to establish a connection."
So far the only attempts I've made towards repair are a Norton Antivirus scan, an AVG scan and a Symantec Qhost removal which came up with nothing.
Does any have any advice on what I could do to fix this without reformatting my hard drive?
It might be worth checking the MTU (Maximum Transmission Unit) setting on your machine. Not sure why this can effect some sites and not others - but it certainly seems to. A friend was recently unable to access hotmail.com until changing the MTU (machine / router)!
check your internet security levels, particularly in IE as it also affects FF.
Link between IE and FF security was revealed some months back during an IE 7 security update. IE fixed it...broke something in IE AND FF for some sites... and IE was "fixed" again (quickly). Whether that condition (link to system layer security) still exists I do not know...but it doesn't hurt to check both when these things happen.