I've left item 9 until you have had time to consider my answers to items 1-8
First a comment about the browsers I am using. When my problems first started I had 3 browsers installed, IE8, Chrome and Firefox, all were up to date. I used Firefox 99% of the time, IE and Chrome only occasionally. Several days ago when rshaffer61 was kindly helping me I deleted IE8 because I thought it might be causing problems. A day or so later rshaffer61 wanted me to carry out some tests which required IE8 so I tried to renstall it. This proved impossible and I got a blue screen with the error message BAD_POOL_CALLER. rshaffer61 thought this might have indicated hard drive problems but a subsequent test on the hard drive showed it to be ok.
Now I have Firefox and Chrome remaining and in all the items below I have tested both and the results have been identical.
Now to your check list:
1. Booted with F8 to Safe Mode with Networking. Problems still exist. I tried logging in as both Owner and Administrator but it made no difference.
2. Internet Explorer - see head note above
3 & 4. Pin commands - I tried both the domain and the ip address for both yahoo and google. Both loaded ok with both the domain, both domain and ip showed similar times. The time element for yahoo was around 220 and for google around 25
5. Problems exist in all browsers in both normal and safe mode
6. Cannot load IE with or without add-ons, do you want me to try disabling add-ons from Firefox and see if the problem still exists?
7. Yes I have used Registry Cleaner type of programmes recently but how recently I cannot recall, whether just before or after the problems started. The ones I had installed were CCleaner, IObit and Advanced System Care. I deleted these as soon as I read in this forum of the inherent dangers. They are now non existent on Add/Remove Programs and do not show on a Windows Search so they appear to have been fully deleted but I do not know if there could be any traces hidden in the Registry.
8. Control Panel Network Connections - the only connection showing is Local Area Connection 3 (Intel PRO/100 VE Network) which is my hard wired connection to my problem pc.
9. I'll hold on this until I hear from you again
Sorry to be so long winded, hope it helps