Maybe try the SEP Support Tool?

http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2008071709480648

-Mike

Thank you but I have already try the SEP Support Toll and I have 0 error !!!

Someone can help me ?
A symantec employee ?

??

We are running SEP MR4 with all our clients at IE 7 and have no issues with them reporting in.  Are they not reporting in at all or only having issues with particular items like Intrusion Prevention Signatures.  I know we have an issue with the clients correctly reporting their IPS status, but I am not comfortable installing MP1 which supposedly fixes this.  I'm probably going to wait until MR5 or at least until all the problems with MP1 and MP1a are resolved.

Are you using the same installation package/policies for the IE 6 clients as the IE 7 clients?

Yes, it's the same

If I uninstall IE7 (so it installs IE6), the communication is OK after reboot (the green dot appears).

I reinstall IE7 and I reboot, and there is no more communication.

I don't understand. It's a real problem...

Please help !

any proxy configuration?

Yes and no !!!
I have this problem with clients with proxy but also with no proxy !

There was something with proxy settings and SEP installation but it was a long time ago (around MR1/2) and don't remember the details but try this:

Build an XP fully patch it and Install IE7 on it.
Export this registry key:
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
Install SEP
Chekc is it working if not then apply exported reg file and check it again.

Thanks for your help pgobu !
But I have already find this solution in another topic.
I tried on different clients but it doesn't works.
Moreover, i have this problem with clients with no proxy !

no more ideas for me.
well you may go with comparing the registry before and after SEP11 installation and check what's going on but it's a hard work.

It has to be something about the configuration of IE, the network, etc.
We have run IE7 for a year, well before SEP was installed. I have IE8 on my own computer. I've seen no communication issues at all, so know it's not the fact that IE 7 or 8 is there, it's something specific there.
Since most people are now up to IE7 and many moving to IE8 (at least those who have not discovered the alternative browsers), if there was a widespread issue, that would be half the discussions here.
So the issue is something specific or unique to that environment.  That needs to be the place to search.
Is IE controlled or configured using AD (active directory) or GPO at all?
Any special settings for IE, or even your Internet access?
Are you blocking any communication types in any way?
How is the network setup? What about control panel, Internet Properties, Connections tab - LAN settings, etc. - when you click that button - there are NO settings, no boxes checked and NO proxy, correct?