Q: Safari can’t open the page “http://+o{i/” because the page’s address isn’t valid.

I am not sure where the URL came from but you are only allowed to have letters, numbers, dots and hyphens in the domain name ie after http:// and before the next /

Here is a valid URL for you to test: http://links.zero.eu.org/

Maybe you accidently set your homepage as that URL?

To re-set your homepage...

1. Press Command-, to open Safari preferences [While you're in Safari of course]

2. Click on the general tab

3. Look for "Homepage:"

4. In the dialog box put what you want as your homepage. [Try http://example.com/]

5. Restart safari and see if it fixes your problem!