Q: safari can't will be connected to the server.

Open System Preferences > Network > Advanced > Proxies

Deselect any checked boxes on the left then click OK.

Quit and relaunch Safari to test.

If it's not a proxy issue, back to System Preferences > Security & Privacy > Firewall

Make sure it's turned off.

Helps to tell us what you have tried that didn't work ...

From your Safari menu bar click Safari > Preferences > Extensions

Turn that OFF, quit and relaunch Safari to test.

Do you have anti virus software installed?

MacKeeper?

MacKeeper is the problem.

Do not install MacKeeper: Apple Support Communities

Uninstall MacKeeper.

Download and install this free utility >  Download AppCleaner for Mac

That will uninstall not only the app but all associated files.

Then restart your Mac and try Safari.

Avoid third party cleaning apps. Your Mac runs maintenance in the background for you > Mac OS X: About background maintenance tasks

Try reinstalling Safari >  Safari 5.1.10 for Snow Leopard

If that doesn't help ..  MacKeeper may have corrupted the startup disk.

Launch Disk Utility located in HD > Applications > Utillities

Select the startup disk on the left then select the First Aid tab.

Click:  Verify Disk  (not Verify Disk Permissions)

If DU reports errors, start up from your Mac install disc to make repairs.

Instructions here >  Mac OS X 10.6: Reinstalling Mac OS X

If Disk Utility reports that the starup disk aperars to be ok, restore OS X from the instructions at that link.

You can't remove MacKeeper using "AppCleaner." Remove AppCleaner according to its developer's instructions, then reinstall MacKeeper and remove it definitively as follows. First, back up all data.

"MacKeeper" has only one useful feature: it deletes itself.

Note: These instructions apply to the version of the product that I downloaded and tested in early 2012. I can't be sure that they apply to other versions.

IMPORTANT: "MacKeeper" has what the developer calls an “encryption” feature. In my tests, I didn't try to verify what this feature really does. If you used it to “encrypt” any of your files, “decrypt” them before you uninstall, or (preferably) restore the files from backups made before they were “encrypted.” As the developer is not trustworthy, you should assume that the "decrypted" files are corrupt unless proven otherwise.

In the Finder, select

Go ▹ Applications

from the menu bar, or press the key combination shift-command-A. The "MacKeeper" application is in the folder that opens. Quit it if it's running, then drag it to the Trash. You'll be prompted for your login password. Click the Uninstall MacKeeper button in the dialog that appears. All the functional components of the software will be deleted. Reboot.

Failure to remove MacKeeper will result from neglecting any one of these points:

Quit MacKeeper before dragging it to the Trash.

Don't empty the Trash after dragging the application to it. Let MacKeeper delete itself.

Don't try to drag the MacKeeper icon in the Dock to the Trash.

Here are some general suggestions. If you want your computer to be usable, don't install crapware, such as “themes,” "haxies," “add-ons,” “toolbars,” “enhancers," “optimizers,” “accelerators,” "boosters," “extenders,” “cleaners,” "doctors," "tune-ups," “defragmenters,” “firewalls,” "barriers," “guardians,” “defenders,” “protectors,” most “plugins,” commercial "virus scanners,” "disk tools," or "utilities." With very few exceptions, this stuff is useless, or worse than useless.

The more actively promoted the product, the more likely it is to be garbage. The most extreme example is the “MacKeeper” scam.

The only software you should install is that which directly enables you to do the things you use a computer for — such as creating, communicating, and playing — and does not modify the way other software works. Never install any third-party software unless you know how to uninstall it.

When all that is done, test Safari. If it still doesn't work, see below.

From the Safari menu bar, select

Safari ▹ Preferences ▹ Extensions

Turn all extensions OFF and test. If the problem is resolved, turn extensions back ON and then disable them one or a few at a time until you find the culprit.

If you wish, you may be able to salvage the errant extension by uninstalling and reinstalling it. Its settings will revert to their defaults. If the extension still causes a problem, remove it permanently or refer to its developer for support.