I have had no problems with Norton and Steam together. I've only seen it complain if Microsoft Security Essentials was installed at thesame time and even that was rare.
Do updates to Norton until it says "updates not required".
Then scan your system. See what pops up.
If its still a problem try turning off autoprotect and firewall. I bet Norton isn't the problem.

If it is Norton, you could try excluding the Steam folder.

Try reading whichever one the links on this Norton support page applies to your version of the antivirus -> How to exclude specific drives, folders, and files from being scanned[www-secure.symantec.com]

Just did that, still error 138

If you're using Norton 360, try disabling the firewall (temporarily), restarting Steam, then trying the Steam browser.

Also, if you use PeerBlock, it can block Steam web access...among other things.

Ok, I figured out it is the smart firewall blocking steam browser. How do I keep the firewall without stoping steam browser (specifically)

Add the Steam client to the list of apps allowed to access the Internet.

i have the same problem, i asddded it to the list of apps allowed to use the internet, but it keeps changing it back to unallowed

im seeling my steam account.but only in provision items.Add ıf you interested