False Connection

[yurka]

The main problem: out of two PCs, the old on e (WinXP) lost its Internet connection, as it appears to me, after I uninstalled COMODO Internet Security. I System Restored the PC to an earlier date and COMODO and Internet connections were restored. Yet, same day later "page cannot be found" popped up again. It is NOT a modem, a router or cable problem: the other PC (Win7) is Okay. The old one has no Internet when connected to the same router or directly to the modem. I reset (I hope, correctly) the Network (no Network now, I exchange files, etc. between the PCs though external HD), released and renewed the IP address and even used Windows repair feature - it informs me that "Windows repaired the problem, please try again".
The latter is part of the minor problem: Windows "think" that there is no problem: it "repaired whatever successfully, clicking the Systray connectivity icon (which always displays 100MB/s speed) System shows that the PC sends packets (although very-very slow!) and even receives packets, even slower. So slow that no page can be downloaded.
Checking for infections with Malware Bytes, S&D, Spyware Blaster was negative, COMODO informs me that there are no threats; I cannot run a scan as it asks me to "select an item (no items are displayed in the blank window!) to launch a scan".
What else can I do? I even replaced the connection cable, more than once! And the other PC has no problems whatsoever, with any cable.

[jdc2000]

Summary of events:

Internet access on the XP computer was working.

You uninstalled Comodo Internet Security on the XP computer.

Internet acces son the XP computer stopped working.

You did a System Restore on the XP computer.

Internet access was restored temporarily.


Questions:

You did not reinstall Comodo Internet Security? A System Restore would not reinstall all components of this software. What happens when you reinstall Comodo?

[yurka]

Questions:

You did not reinstall Comodo Internet Security? A System Restore would not reinstall all components of this software. What happens when you reinstall Comodo?

I did NOT reinstall COMODO, it was in the PC after SR was done, I managed to update it, as my ultimate goal was to install COMODO antivirus, yet I was informed by COMODO that my version was so old that first I had to update it. I still could not download COMODO AV, as by then I lost connection again.