If your machine is not always connected to the internet see self hosting the jquery files, the errors could happen if it is failing to load the scripts from the google cdn.

xp is not something I would use for a web server or even development these days. Only other suggestion is make sure you have the latest versions of .NET framework and all updates installed.

use browser tools to make sure that the javascript is loading, ie look at the network tab in browser tools for any scripts that may be failing to load.

I guess IE 8 doesn't have it. Really it should not be browser specific so you could use chrome or firefox on the same machine to see if they fail to load any files. Otherwise in IE 8 I would view the source of the page and sequentially test each and every link to javascript by copy and paste the url into a new browser tab. Then you can find out if any errors are happening in requesting those files, ie you will either get javacript in the response (which means it should be loading in the browser), or a server error, or 404 file not found. I would start with the jquery files since those errors indicate a problem with jquery.

No, its loading that one according to your screen shot and the error is happening in that file because it depends on jquery which is not loading.

You did not correctly configure the locally hosted jquery files that is what you need to resolve.

well now you're talking about design issues and IE 8 support. To be possible to even try to help with that would require seeing the site, ie you would have to post a public url to the site that is accessible over the web, can't really help on a private network.

I would like to see a screenshot from fiddler now that you fixed it because it was failing to load the jquery css before and that does not cause script errors but does cause design issues. I would double check whether you fixed that one.

the screen shot shows everything is loading ok so the jquerycss is not the problem.

I cannot help further, there is no way to resolve design issues by guessing, even if I could see the site I'm not sure I would have any quick css advice. Browser specific or IE specific issues can be tricky to resolve and can take lots of trial and error.

The css and other skin files used are located at

/Data/Sites/[SiteID]/skins/[SkinName]

the css files are combined in the order that they are listed the style.config file in that folder.

After editing any css you should go to Administration > Advanced Tools > Design Tools > Cache Tool and click the button to reset the skin guid. This ensures the browser reloads the css instead of using its own cache.

Most of the skins we include were made in Artisteer. The latest versions of Artisteer target html 5 and therefore the IE 8 support may not be as good.

If you have a lot of IE 8 users to support you might have better luck trying some of the older skins included in the extra-skins.zip on our codeplex download page.