Cannot connect to office 365 with windows XP and outlook 2010

A pc with windows XP and outlook 2007 used to connect to office 365 suddenly stopped working, Outlook was left open and logged in over night, when checked in the morning outlook had disconnected and was asking for password. When the password was then entered it wasn't accepted. No updates had been applied over night. As I'd had a similar issue last year which was fixed by running the office 365 desktop setup I ran it again to check for updates and installed any that were needed. Still wouldn't log in. so I upgraded to office 2010, re-ran the office 365 desktop setup, installed the required patches and updates and let it configure what it could. It told me that outlook needed configuring manually. Tried configuring a new outlook profile both with autodiscover and manually and both fail. When setting up the outlook profile " establish network connections" and "search for server settings" are successful but log in to server fails. It asks you to check the name and when you do you get "the name cannot be resolved. the microsoft exchange server address book was unable to log onto exchange". If I then try to log into outlook I get "the microsoft exchange server address book was unable to log onto exchange"". The email account works fine on another machine that is vista and outlook 2007. If it's any help Lync still works but I have to manually add proxy settings to get it to work, but it has always been like that. One strange thing is that when I try to log into the old outlook profile (that was working before the issue), the login box shows "connect to, connecting to" (I have replaced my real email address with for privacy) , whereas on the vista pc that works it shows " "connect to, welcome back to".
This is only happening on one PC. The PC in other respects has no issues, can still access the internet, and can access office 365 through the portal with no problems.
There is another PC that is also XP and office 2007 and can connect fine with another user's mailbox (am unable to try with my mailbox).
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JohnBusiness Consultant (Owner)Commented:
XP has been dead for a year now and no security patches have been supplied. XP is easy to hack. Check carefully for viruses with your own AV application and then see if you can run Malwarebytes.

If the virus scan comes up clean (does not mean no operating system damage), try to run TCP/IP Reset and DNS Flush to see if that helps.

Open cmd.exe with Run as Administrator
Then  netsh int ip reset c:\resetlog.txt
Also, ipconfig /flushdns followed by net stop dnscache followed by net start dnscache
Then restart the computer
I am getting exact same problem with an XP client yesterday, and a second XP client today.

Googled the specific error msg, and there is one result in Google, from office365 admin from yesterday (1/4/2015)

Looks like a nice Microsoft April fools to force everyone to upgrade from XP:
karenbarryAuthor Commented:
thanks for this info. Glad I'm not going mad! How annoying that it seems like Microsoft have changed something and not notified anyone. Oh well I might have to bite the bullet and upgrade. Interestingly there are also errors in event viewer from about 1.30am 1/4/15 relating to DNS - event id 40961 the security system could not establish a secured connection with the DNS.... and The security system detected an attempted downgrade attack for server DNS... etc event id 40960
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JohnBusiness Consultant (Owner)Commented:
Oh well I might have to bite the bullet and upgrade.

Yes. Even Windows 7 is now past its best before date and living on life support.
I raised this issue myself on EE yesterday, and one of my contributors is telling me Microsoft have resolved. Sounds good, but also sounds unlikely that they would resolve an XP issue.

Am away from office today, so not able to verify...
karenbarryAuthor Commented:
I've just checked and still not working for me..
karenbarryAuthor Commented:
Seems like Microsoft have fixed it over the weekend as it's now working again

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Issue seemed to be sorted for some XP users, but not all, and only resolution was to bite the bullet and upgrade the client to Windows 7...

It was very disruptive that it occurred so suddenly, but in the long run it was good to get some XP clients upgraded, even if that course of action had been forced by circumstances outside our control...
karenbarryAuthor Commented:
Refer to the microsoft link shown in this thread for explanation that is was a microsoft issue that they have now fixed
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