Cannot open Google, and some other websites..

What happens when you try to load those sites?

Have you restarted your router and your broadband device (if they're separate) since you first noticed the problem? If not, please do that now and see whether there's any change.

Unplug the power adapter, and plug it back in.

Are you in China, or another country with Internet restrictions?

Double-click anywhere in the line of text below on this page to select it, then copy it to the Clipboard by pressing the key combination command-C:

www.google.com

Launch the Network Utility application.

Step 1

Select the Lookup tab and paste into the address field (command-V). Press return. Post the output that appears below – the text, please, not a screenshot.

Step 2

Select the Ping tab and do the same. Please enter the same input as you did in Step 1. Don't use the output of Step 1 as input to Step 2.

Important Note

Some web browsers and mail clients will automatically convert a domain name such as "www.example.com" to a clickable URL, such as http://www.example.com. That will interfere with the test. If necessary, edit the input in the Network Utility window to remove any added characters.

Please read this whole message before doing anything.

This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.

The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.

Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem. You must hold down the shift key twice: once when you boot, and again when you log in.

Third-party system modifications are a common cause of usability problems. By a “system modification,” I mean software that affects the operation of other software — potentially for the worse. The procedure will help to identify which such modifications you've installed, as well as some other aspects of the state of the system that may be pertinent.

Don’t be alarmed by the seeming complexity of these instructions — they’re easy to carry out. Here's a brief summary: You copy a line of text from this web page into a window in another application. You wait about a minute. Then you paste some other text, which will have been copied automatically, back into a reply on this page. The sequence is: copy, paste, paste again. That's all there is to it. Details follow.

You may have started the computer in "safe" mode. Preferably, these steps should be taken while booted in “normal” mode. If the system is now running in safe mode and is bootable in normal mode, reboot as usual. If it only boots in safe mode, proceed anyway.

Below are instructions to run a UNIX shell script. It does nothing but produce human-readable output. However, you need to be cautious about running any program at the behest of a stranger on a public message board. If you question the safety of the procedure suggested here — which you should — search this site for other discussions in which it’s been followed without any report of ill effects. If you can't satisfy yourself that these instructions are safe, don't follow them.

Triple-click anywhere in the line of text below on this page to select it:

clear; PB=/usr/libexec/PlistBuddy; PR () { [[ "$o" ]] && o=$(sed 's/^/ /' <<< "$o") && printf '\n%s:\n\n%s\n' "$1" "$o"; }; PC () { o=$(egrep -v '^[[:blank:]]*($|#)' "$2"); PR "$1"; }; PF () { o=$($PB -c Print "$2" | awk -F'= ' \/$3'/{print $2}'); PR "$1"; }; PN () { [[ $o -eq 0 ]] || printf "\n%s: %s\n" "$1" $o; }; a=$(id | grep -w '80(admin)'); [[ "$a" ]] && sudo true && r=1 || r=; { [[ "$a" ]] || echo $'No admin access\n'; [[ "$a" && ! "$r" ]] && echo $'No root access\n'; system_profiler SPSoftwareDataType | sed '8!d;s/^ *//'; o=$(system_profiler SPDiagnosticsDataType | sed '5,6!d'); fgrep -q P <<< "$o" && o=; PR "POST"; o=$(($(vm_stat | awk '/Pageo/{sub("\\.",""); print $2}')/256)); o=$((o>=1024?o:0)); PN "Pageouts (MiB)"; s=( $(sar -u 1 10 | sed '$!d') ); [[ ${s[4]} -lt 90 ]] && o=$( printf 'User %s%%\t\tSystem %s%%' ${s[1]} ${s[3]} ) || o=; PR "Total CPU usage"; [[ "$o" ]] && o=$(ps acrx -o comm,ruid,%cpu | sed '2!d'); PR "Max %CPU by process (name, UID, %)"; o=$(kextstat -kl | grep -v com\\.apple | cut -c53- | cut -d\< -f1); PR "Loaded extrinsic kernel extensions"; o=$(launchctl list | sed 1d | awk '!/0x|com\.apple|org\.(x|openbsd)|\.[0-9]+$/{print $3}'); PR "Loaded extrinsic user agents"; o=$(launchctl getenv DYLD_INSERT_LIBRARIES); PR "Inserted libraries"; PC "cron configuration" /e*/cron*; o=$(crontab -l | grep [^[:blank:]]); PR "User cron tasks"; PC "Global launchd configuration" /e*/lau*; PC "Per-user launchd configuration" ~/.lau*; PF "Global login items" /L*/P*/loginw* Path; PF "Per-user login items" L*/P*/*loginit* Name; PF "Safari extensions" L*/Saf*/*/E*.plist Bundle | sed 's/\..*$//;s/-[1-9]$//'; o=$(find ~ $TMPDIR.. \( -flags +sappnd,schg,uappnd,uchg -o ! -user $UID -o ! -perm -600 \) | wc -l); PN "Restricted user files"; cd; o=$(find -L /S*/L*/E* {,/}L*/{A*d,Compon,Ex,In,Keyb,Mail/Bu,P*P,Qu,Scripti,Servi,Spo}* -type d -name Contents -prune | while read d; do ID=$($PB -c 'Print :CFBundleIdentifier' "$d/Info.plist") || ID=; ID=${ID:-No bundle ID}; egrep -qv "^com\.apple\.[^x]|Accusys|ArcMSR|ATTO|HDPro|HighPoint|driver\.stex|hp-fax|JMicron|microsoft\.MDI|print|SoftRAID" <<< $ID && printf '%s\n\t(%s)\n' "${d%/Contents}" "$ID"; done); PR "Extrinsic loadable bundles"; o=$(find /u*/{,*/}lib -type f -exec sh -c 'file -b "$1" | grep -qw shared && ! codesign -v "$1"' {} {} \; -print); PR "Unsigned shared libraries"; o=$(system_profiler SPFontsDataType | egrep "Valid: N|Duplicate: Y" | wc -l); PN "Font problems"; for d in {,/}L*/{La,Priv,Sta}*; do o=$(ls -A "$d"); PR "$d"; done; [ "$r" ] && { o=$(sudo launchctl list | sed 1d | awk '!/0x|com\.(apple|openssh|vix\.cron)|org\.(amav|apac|calendarse|cups|dove|isc|ntp|post[fg]|x)/{print $3}'); PR "Loaded extrinsic daemons"; o=$(sudo defaults read com.apple.loginwindow LoginHook); PR "Login hook"; o=$(sudo crontab -l | grep [^[:blank:]]); PR "Root cron tasks"; }; o=$(syslog -k Sender kernel -k Message CReq 'GPU |hfs: Ru|I/O e|find tok|n Cause: -|NVDA\(|pagin|timed? ?o' | tail -n25 | awk '/:/{$4=""; print}'); PR "Log check"; } 2> /dev/null | pbcopy; exit

Please note:

☞ This procedure is all copy-and-paste — type only your login password when prompted. When typing it, you won't see what you're typing. Make sure caps lock is off.

☞ Remember to post the output. It's already in the Clipboard when you see "[Process completed]" in the Terminal window.

☞ If any personal information, such as your name or email address, appears in the output, anonymize it before posting. Usually that won't be necessary.