Saw an announcement on Comodo Site Inspector, which scans sites for malware, so ran the first of the urls on the search through it. Reported as safe, for what that is worth. BTW, the "go to .677" looks like a stock answer, not an indication that the problem doesn't occur there.
un-installed 5.1.889, rebooted used the avast un-install utility, rebooted cleaned registry, rebooted twice, installed .677 rebooted twice. checked those sites again - same problem. Checked sites with URLVoid and they tested OK.
I was too lazy to go back and read from the beginning of the post at this time, so I may accidentally repeat something that was already mentioned, if that happens; I would like to apologize in advance.
Anyway, you definitely need some help Boss, and I will try to see what I can do for you.
Have you ever switched your DNS service and/or Host File?
If not, how about a little experiment, try downloading the ClearCloud DNS utility and enable ClearCloud DNS and see what happens.
Also if you have not done so already make sure Windows is up-to-date, run CCleaner, try running IE/Chrome/Firefox in InPrivate/Incognito/Private Mode, see what add-ons/plug-ins are set to run.
Also try clearing All data from the browser options of each browser, if you have not done so, which I think you already have.
Download Emsisoft HiJackFree and save the log & post it here, and maybe we can see if anything suspicious shows up in it.
Also you may want to also download Comodo KillSwitch and save the log from that & post it here as well, but it is Beta and you may have to log into the forum to download it; so do not worry about it if that is the case, since HiJackFree's log will probably have almost all we need.
Also download and install Secunia PSI and/or FileHippo Updater (I use both) and scan to see if it/they show any of your programs as being out-of-date.
Try running a Avast Boot Scan on Highest Detection Setting (Thorough) and set to scan All Local Drives, if you have not done so already, and maybe even setting most of your Avast settings on High such as: Scan Whole File, Scan For Potentially Unwanted Files, uncheck this one setting for persistent cache of safe files to never be scanned again even after rebooting, etc.
Heck even try a full Malwarebytes scan, Windows Defender (hahaha), Norton Power Eraser, Hitman Pro.
Hmmm, I wonder could some malware had changed your Host file?
Also what if some Flash Cookies or something are the problem!?
Try going to the Adobe Flash Player Global Settings Manager and setting it to store None in several of the categories where you have that option and delete any entries that have been saved and/or use the Better Privacy Firefox plug-in and set it to automatically delete them on the close/exit of the browser without asking, delete flash player default cookie, and empty cookies folder.
We are going to fix this Boss, let me know what happens, we will win this battle!
For BigBro! *Dramatic Battle Music*