+1 the above, run as many different AV scans as possible, just a reminder to not install their "active" components (you really REALLY only want one antivirus running at a time. Running 2 doesn't protect you better, it will screw you up).
If you have any downloaded toolbars for your browsers, especially ones you got just recently, try removing them.
Then if it's still funky, DL "HiJack This" from Trend Micro, run "Scan" to get the list of startup processes/BHO/suspicious stuff, and look through it especially for suspicious BHO. The list is really unfriendly to look through, do a "Save Log" and paste it into their analyzer
http://www.hijackthis.de/index.php which does give a few false ? - like it doesn't recognize some recent Steam processes, or Desura, or a few of my drivers. Mine is relatively clean because I try to DL a minimum of junk to run/display in toolbar/add to browsers. Don't just disable stuff willy-nilly most of it is normal stuff - if you get stumped post it in their forum for somebody to analyze.
It's a good idea to save a copy of the Log file periodically so you can compare entries, and see what kind of new stuff has been snuck onto your system.
Another thing is, if you don't have a good path to google.com, whenever you click on a google search result, or even a lot of times you enter an address in the bar, you don't go directly to the site you go thru a redirected url to google.com first so they can track it, THEN you are redirected to the site you wanted. Once in a while, when there was some problem between me and google I noticed this slowed down things enough that some sites wouldn't load the 1st time even though google was only a bit slow but otherwise OK. You might try switching to a search engine that doesn't do this, like duckduckgo, change it as the default in your browser, and see if this makes the problem go away.
Edit: Oh yeah, try briefly turning off your antivirus too, every once in a while they make a change that loads down your system with excessive checking - like it will try to look up any link you click in a databse of "bad sites", on top of several other checks - sometimes they overdo it, especially in combination with a slow pc/not-quite-reliable internet connection, and the result can appear similar to what you describe. If you've got a bunch of add-on plugins to check urls, try temporarily turning them off too.
Also, check the obvious - fire up Task Manager and make sure your cpu isn't pegged at 100%, that you're not using virtual memory way greater than the physical memory you've got installed, and that you're not running some torrent program or something that's eating 100% of your bandwidth.
Ed 2: Yet another thing - open a command window and type "ping -t google.com" and let it run while you're using the computer. Elongate it so it's a long window so you can see lots of results - as big as your screen. When you encounter one of the pages that won't come up, quickly switch to this window and see if the ping times went way up or even lost packets. Instead of google.com, try different sites, maybe one you keep having trouble with...
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Topic: My computer is acting up! (Read 1512 times)