Computer won't allow some programs to connect

November 23, 2011 1:03 AM

Recently, my computer has decided to be very particular about what it will allow to connect to the internet. Some programs, like uTorrent and Filezilla, can connect fine and have no problems. But things like self-updaters and Flash-based uploading cannot connect. The same thing happens on two different internet connections on two different wireless networks whose configurations have not been changed since before this started (I do not have a wired network to test). I have not made any significant changes to my computer since before this started. I'm running Windows 7 x64 Ultimate. What could be causing the problem? How can I fix it? What caused the problem in the first place?

I first noticed the problem on November 10 or 11, when iTunes could not download an update -- even though it was able to find out that an update was available. Microsoft Security Essentials has run several full scans since then and found no problems. I've checked Windows Firewall and that doesn't seem to be the thing that's blocking the connections. I do not normally make any connections through a proxy. The hosts file is fine, I've flushed the DNS cache multiple times, tried an alternate DNS, turned off MSE's real-time protection (and then back on when it made no difference), and turned off Windows Firewall (and then back on).

Here are some things that DO NOT work:
-Windows Update
-iTunes update, store, and radio
-Flash self-updater
-Microsoft Fix It
-Steam store and news
-Gmail's default uploader for attachments
-Imageshack's default uploader
-Imgur's default uploader
-Flickr's default uploader
-DSLReports' Flash speedtest

Here are some things that DO work:
-uTorrent
-Filezilla
-Firefox (aside from the things mentioned above)
-Tor
-Netflix Watch Instantly (though it sends data in bursts instead of a constant stream)
-Youtube (same as Netflix)
-Steam client and game updates
-HTML file uploaders for the sites listed above
-DSLReports' Java speedtest
-MSE definitions updating

posted by clorox to Computers & Internet (9 answers total)

I just ran into a problem with similar symptoms (weird packet loss and latency issues) and eventually traced it back to some older hardware with poor ipv6 support. You could try disabling ipv6 in your network adapter and refreshing the connection.
posted by grizzly at 1:10 AM on November 23, 2011

Have you tried system restoring your computer back to before you noticed the problem? (All programs->Accessories->System tools->system restore). November 8 was a patch Tuesday and you first noticed the issue two days later, I wonder if your computer downloaded some bad wireless drivers from Windows Software Update or something like that.
posted by phoenixy at 3:20 AM on November 23, 2011

If you also can't get to any a/v site, suspect malware. Some malware blocks these to make it harder to disable the software.
posted by eriko at 3:25 AM on November 23, 2011

Have you tested it with a wired connection?
posted by dgeiser13 at 6:33 AM on November 23, 2011

I ran into this recently and the cause was a bit of malware that had installed a proxy and was filtering all traffic (and data, bad news!) through its own server. In win7 just type "proxy" into the start button bar thinger and pick "configure proxy server". It should be blank, unless you need one.
posted by TomMelee at 6:51 AM on November 23, 2011

Is it possible to test any of those using a live CD? How about using a different wifi connection? It would be good to distinguish between something weird on your computer (probably malware) versus something weird happening upstream.
If you packet-log the update attempts or try to connect using telnet, do they time out, fail to connect with specific errors, or fail later on?
posted by marakesh at 7:06 AM on November 23, 2011

I vote for Malware. Run Malwarebytes and SuperAntiSpyware.
posted by cp7 at 7:32 AM on November 23, 2011

Check your hosts file-- even if you've cleaned out the malware, some resiue may be left behind. Spybot has, I believe, a hosts file editor, but you can always drill down to find it at
%systemroot%\system32\drivers\etc\

The only thing you absolutely should have in there is a match between localhost and 127.0.0.1, and anything else there would've probably been added by software such as ad-blocking, or else certain malware, to re-direct your requests.

Is someone else in control of your internet connection? They might be running a blacklist or some variation on Upside-down-ternet.
posted by Sunburnt at 9:22 AM on November 23, 2011

Response by poster: For some reason the problem fixed itself. Thanks for the replies!
posted by clorox at 9:46 PM on December 5, 2011