w7 pro internet connection blocked by some virus or program

hello experts
something weird happens with w7
network shows connection to the internet fine
but i cannot see any network computers and cannot access the internet!
- windows updates cannot access the internet for 1 year already
- windows time cannot access the server and cannot be updated
- antivirus avast cannot access the internet

i installed avast using USB and scanned it for viruses. avast found bunch of viruses and deleted them ...
also i run windows malware -- it also "found and fixed" however the problem is the same!
nothing can access the internet! NOTHING!

at the pc was installed Factory Talk Software which works fine and connects to PLC fine locally....
but PC hasnt been updated for around 1 year

also when i run antivirus avast it told me that some program is blocking it .....

could you please advice how can i check what program took over the PC control .... ? or something ...
looks like all ports maybe blocked ....

regards
LVL 4
nzrubinAsked:
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JohnBusiness Consultant (Owner)Commented:
Scan again with Avast and then scan with Malwarebytes (malwarebytes.org).

If the viruses are bad enough, back up everything, and reinstall Windows.  If you have a recovery partition to do this, use it to delete all other partitions, format and reinstall Windows. If you do not have a recovery partition, delete all partitions, format and reinstall Windows. WHY? Because root kit viruses can survive formatting.
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VB ITSSpecialist ConsultantCommented:
I agree with John, a complete wipe of your OS may be the way to go here as it sounds like your machine has been deeply infected. Back up whatever files you can to an external drive then reinstall Windows from scratch.

Without knowing what you have been infected with, it will be very hard to identify and remove the malware.
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nzrubinAuthor Commented:
thanks for replies!
the only program that can access the internet its a Factory Talk (alan bradley PLC software)
it connects using open port ...
can this program block all the other ports ?

regards
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Rob GMicrosoft Systems EngineerCommented:
I would check a few things before i reinstalled everything..
AV's tend to give false positives, and there are also some things that can cause this locally without it being a virus..

Press the windows key on the keyboard.. and the R key at the same time.
In the run area type in CMD and press OK
There will be a black box that pops up..
Type in "Ping google.com" (without the quotes) and see if you get a reply or if you get something else.
If you get a reply..
Take that number.. 123.123.123.123 and type it into your browser and see if you can get to the page. If  you can, this is simply just a DNS issue, or possibly a virus that has hijacked your hosts file, which is simple to fix, and will save you hours to repair your PC.

Alternately you can use another machine to go:
http://www.avg.com/us-en/avg-rescue-cd

and download the free boot CD.
This will scan the machine at boot, which is F8 on the keyboard at boot (Dell) and boot from CD.
It will run a full scan and likely fix the issue on boot..
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nzrubinAuthor Commented:
thanks for advise!
when i ping google. com the reply is dead!
host cannot be found!
also CD rom stopped working so i cannot use it

i will try now to use avast usb rescue (Rob G give me a hint, thanks)
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JohnBusiness Consultant (Owner)Commented:
@nzrubin  - Thanks, and I was happy to help.
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