Safari (updates and itunes store) can't connect

Question

When using Safari on my home network I cannot connect to any website. I will get messages such as "Safari can’t open the page “http://www.apple.com/” because Safari can’t connect to the web proxy server (HTTP). To change your proxy settings, open Safari Preferences, click Advanced, and then click Change Settings. For help with this problem, contact your system administrator." I am the network administrator. Also itunes store, and software updates will not connect. Entourage and mail receive mail but with question marks instead of images. Firefox has no problems, and when running network assistants diagnosis all seems OK - all green lights.
My son's identical MacBook (with seemingly identical network airport settings, but running 10.5) will connect to the iTunes store and also to websites using Safari, as will both of our ipod touches. My MacBook will actually connect to the iTunes store using my same network when running WinXP using vmWare fusion.
I have tried to change Safari's proxy setting through its preferences, but the Proxies>change settings button is ghosted - so I have accessed the network settings for my home location to ensure that no proxy checkboxes are checked. (I have tried automatically detect proxy settings, but still no go). I have created new network locations and tried many combinations of settings (network assistant's diagnosis is always all green lights, whenever I have used it.)
I have also emptied the system configuration folder from preferences (along with com.apple.internetconfig.plist, com.apple.internetconfigpriv.plist, com.apple.internetconnect.plist) and rebooted with no joy.
I have ensured that I have the current versions of Safari and iTunes installed and am at a loss. I don't know when this first happened, and can't think of a change that I have made that would have precipitated this. Safari does function at work on the work's network, and images do come through to my mail at work. I am assuming that I have a setting at home that is blocking. (I have turned my firewalls off and on to check, but again no success.)
I am about to buy an iPhone and am waiting til I can sort this issue. Any suggestion would be appreciated.
Thanks,
Richard.

Answer 1

HI,
From the Safari Menu Bar, click Safari / Empty Cache. When you are done with that...
From the Safari Menu Bar, click Safari / Reset Safari. Select the top 5 buttons and click Reset.
If you have Safari 3rd party plugins, they may not be compatible with 10.6. Go here for trouble shooting.
If you use GlimmerBlocker by chance, that could be the culprit. Check out this thread.
http://discussions.apple.com/thread.jspa?messageID=10589731
http://support.apple.com/kb/TS1594
Same with any Input Managers. Move any files in the /Library/InputManagers folder to the Trash
If you are running Safari in 64 bit mode, try running in 32-bit mode instead. Right or control click the Safari icon in the Applications folder, then click: Get Info In the Get Info window click the black disclosure triangle next to General so it faces down. Select 32 bit mode. Also, (in that same window) make sure Safari is NOT running in Rosetta.
Go to ~/Library/Cookies and move the Cookies.plist file to the Trash.
Try Open DNS - Free / Basic
If Safari still can't open web pages, go to the Menu Bar, click Safari/Preferences. Make note of all the preferences under each tab. Quit Safari. Now go to ~/Library/Preferences and move this file com.apple.safari.plist to the Desktop. Relaunch Safari. If Safari loads web pages then that .plist file needs to be moved to the Trash.
Carolyn