You can follow this document , if its professional its not supported first install LU and then install SEP

https://www-secure.symantec.com/connect/forums/windows-7-profession-1105-wont-install-rolls-back

https://www-secure.symantec.com/connect/forums/endpoint-wont-install-fresh-install-windows-7

What do you mean - SEP RU5 is not support on Windows 7??

Ya know, this is getting a bit silly isn't it?
Seems to me that there's a huge issue with all thes folks coming in and stating they can't push SEP to Windows 7.
Network admins and others don't have time to hold hands on a CENTRALLY MANAGED AND DEPLOYED software. Sort of defeats the purpose, doesn't it? I mean, really - the fix is to start over and install each little piece by itself - to 350 computers?
We'll be putting Windows 7 out there coming up - and it won't be pretty if we have to deal with this on a PC by PC install basis for hundreds of computers all over Iowa........

I'd say - stop with the band-aids and fix it..........fix what's obviously wrong with the install processes for SEP packages. Let's not rely on the consumer to have to jump hoops.

Was this not seen in beta testing? I'm seriously quite confused - I've never seen so many complaints of the exact same issue in such a short time except in the cases of bad definitions being rolled out.................

Hi,

Installing Live Update 3.5 and Installing the RU5 client completes the installation.
However, doing this process on multiple instances ends up in BIG task. :(

Try by installing in other computers in normal way and see whether it is giving any problem... 

Not sure where Rafeeq got the information that Windows 7 isn't a supported OS with RU 5, but I assure everyone it is.

We do QA test our software...quite extensively, as anyone who's been around Symantec software, and seen release dates pushed back multiple times, can attest to.  However, it is flatly impossible to test every configuration.  We try to test against as many configuration scenarios as we can.

I dunno, I wasn't able to get into the beta.......... but this sure seems like a BIG one to have missed, sorry! It just seems that install failures with LU involved apparently are not new, as we were facing them here with MR4 when I was working with support attempting to get a reinstall on our file server here. It failed constantly and ended up being a LU failure. We had to remove LUCHECK from the package to make it go. That was MR4. Now I see all these with RU5, same symptoms, all these in the forum, and wonder how many folks don't post it here, or call support instead or find other solutions. You can bet, as a support person, what you see reported is typically only a very small percent of what really exists, but folks either figure it out, or call, or get it solved in other generic IT forums.
It's starting to worry me - however, since I saw that same issue here, with MR4, and we'll be hitting Windows 7 in a few weeks...... and there's no way we can manually install like that.
I guess I'll have to do a few test machines and see what happens here................  I hope it's being worked on, though - as I can assume some folks will see the issues just attempting to install to hundreds of computers and be a bit aprehensive. It's a bad taste right out of the box.....
(having done beta testing for roughly a decade with Symantec, I also know that there were, at least a few years back, intense deadlines in the testing - we used to get builds in the mail early in the week, and read the documents and find we had to post results that same week............as the next build was coming the following week. I've not done beta testing for a few years, however, so maybe those VERY tough deadlines imposed on beta testers have been relaxed a bit. But back then, we had to really dedicate a lot of time on it, and often were not able to fully get through the test scripts if we also had full time jobs. I found most of my bugs by not following the scripts, however, as most end-users won't follow the directions anyway. So you have to think like a real customer, throw away the documents, install over old builds and hope for the best.  LOL )

I saw that "unsupported OS" comment and it really bothered me! Wait, ALL of Windows 7, all versions, are supposedly supported...... but wait, in support, it's said not all are?

In the registry,

Find

HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders\AppData
value=%APPDATA%

and change it to

HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders\AppData
value=%USERPROFILE%\AppData\Roaming

Install SEP client again.

http://service1.symantec.com/support/ent-security....

In sad news, my client already had the adjusted registry as above.

The SEP marks as successfully deployed in my Console, arrives and attempts to uninstall in the client system and then just as it is about to finish, it reverses and dissappears.

The next time I search for unmanaged computers via the IP, theclient is listed again.

What's going on Symantec????

If it smells like and squishes underfoot like a turd, I don't care what you call it.

thank you anoobi, 

that fixed the installation for me.been driving people nuts with the isntallation not working.