Same problems I have been going through for about 10 days ...
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(1) Cannot download windows updates gets stuck -- sometimes just white
screen -- or page not found error etc === all my windows services settings
are as suggested/recommended.
(2) I cannot access Yahoo, Google and many other sites. I reloaded IE 7,
tried firefox - no use.
(3) I have been paying for a full suite of tools from McAfee - they did not
find anything - I tried to update their software - browser gets stuck on
their websites as well.
(4) I ended up downloading PC Tools scanners Spyware Doctor (their website
did work) -- and it found various spyware -- dont know how i got them if I
already have McAfee that is supposed to be protecting me

) == I had to
purchase PC Tools product to actually clean what it found == long story short
-- NO USE after all the clean up it did. I also tried Windows OneCare online
tool -- it did not find anything wrong either.
(5) Bottom line -- browser doesnt work on many sites including Yahoo,
Google, windows updater, McAfee download pages == browser does work well on
Wimbledon website

) I have been watching scores and following tennis and
praying that my computer will get better -- reading all the message boards
--- trying everything that I have not tried so far == I will try getting some
preist/guru/pandit/rabbi to come and bless my computer.
(6) BTW ... I am not a total idiot when it comes to computers -- though I
dont manage/maintain them for living - i know little about them. I talked to
some experts in town that I know -- they said they have seen the same problem
before, but those computers they dealt with were not very important/critical
-- so they just reinstalled everything starting from a clean slate
(7) i started backing up my important files and waiting for some miracle to
save my computer -- I like not to go through total re-install if possible.