Windows 7: Outlook 2007 and Win 7

No previous problems with Outlook and XP. New clean Win 7 installation and now random failures to send emails.
Tried repairs to Office/ Outlook; Uninstalling Norton; fresh set up for each of my email accounts but nothing cures it. Same addresses are rejected with message from System Administrator that "has not been delivered to following Recipients:" - but no details. Failed emails show up in "Sent" folder but account of sender has been changed from david to sue or sue to rod. Test messages between these go through ok. Is this a win 7 problem because I have tried everything associated with other programmes that I or my friends can think of?

Outlook 2007 is running fine for me, so not sure what the problem is, other than you might have entered a wrong character or something setting up your mail.

Same here. Windows 7 and Outlook 2007 are working fine. Haven't heard about any issues like your.
I doubt if the issue is with Windows 7 as it has nothing to do with email sending or receiving.
If you have a backup copy of your Outlook pst file I would consider using it.Also you may have a virus running around sending emails out with ficticious address.
I have heard about viruses doing that awhile back but nothing recent.
Run Malewarebytes and your virus scanner for sure.

Good luck and keep us posted.

Thanks FZ21Z but it is not as simple as that. I have tried retyping dozens of times and deleting and re-entering account details likewise. How do you explain change of sender?
IggyAZ- Clean install of Win 7 which necessitates new install of Office and therefore .pst files. Numerous Office repairs and un-install/ new install twice. New Norton Internet Security fully updated and even had Norton Support take over my machine and found nothing associated with virus or actions of Norton.
macpike - I love Win 7 and wondered about replacement of ActiveSync but Mobile Device Centre works superbly well with my Ipaq
BTW my problem is not the ISP because I can send to same people with my laptop on Outlook and Win XP.

Perhaps some add-in is causing a problem? You could try running Outlook in safe mode: go to the Run box at the bottom of the Orb menu and type

outlook.exe /safe

and see if that fixes it, then please report back

My safe mode suggestion was to greenwellington, whose thread you have kind of hijacked

How about starting a new thread about the calendar issue, which will probably attract more expert interest as well keeping things nice and tidy? Meanwhile I will have a think about the sync

Thanks Clunkfish - that was an option I hadn't thought of.
Before I try that, will I come out of safe mode next time I start Outllook?

Yes - if you start Outlook from the Start menu or a shortcut or whatever you usually use, it will start normally.

If the /safe switch cures things, we can start to look for a culprit add-in; if it doesn't, we can think about other alternatives.

Sorry to be so dumb Clunkfish but get this message:
"Cannot start Microsoft Outlook. The command line argument is not valid. Verify the switch you are using."
[IMG]file:///C:/Users/David/AppData/Local/Temp/moz-screenshot.png[/IMG]

Have you got the syntax right? If you type in the "Search programs and files" field that is at the bottom of the window that opens when you click the start orb:

outlook.exe /safe

with a space between outlook.exe and /safe, it should work....