outlook & outlook express

hi guys.. i got a very frustrating problem.... hope if we can narrow down this issue..

I got many many people coming up and asking for this issue... no concrete solutions....

In outlook and outlook expres there is a major issue with error's like 0x800ccc0d, 0x800ccc0f and to add more at times a screen saying " enter network password " keeps poping again and again...

It's been pain in the butt even though all the settings are correct..
following steps iv aready taken:-

1. i'v confirmed the settngs with the ISP
2. checked with microsoft they say that its nt an issue with outlook or outlook express
3. checked with antivirus and firewalls ( norton,mcafee etc)
4. instead of the names of pop and the smtp settings used there ip address instead
5. member is abel to get into the web mail using the same id and the password...
still no concrete solution to these kinds of error messages,

at times 0x800ccc0f and 0x800ccc0d errors are fixed after desabling norton but not everytime,
still no solution for the screen that asks for " enter network password"...
its making it almost impossible to zero down the possible problem and find a fix to these problems...

did a research on this checked with many forums and sites... no one has a correct fix to this.... in many sites i got some links to update the registries... stilll no proper resolution.......... most common thing every one said was" it worked fine till now and now i have this problem it keeps on coming every now and then fixes on its own after two three days and starts happening again"

Possible bug in outlook express or outlook itself ?
Does it have anything to do with MTU size?

Im not shure what to answer to my customer's ?
I'll really really really appreciate any resolution to this.. even if it needs to contact the microsoft software developers ( which is nearly impossible)...

thnxx in advance......

Check the link below and see if it helps any.

support.microsoft.com/default.aspx?scid=kb;en-us;813514#top

www.nthelp.com/50/Outlook_error_codes.htm

thnx a lot buddy..
certainly got lot of help... just to share with u the problem was at the ISP end and at times it was the linksys router with a low MTU size...