Help with lsass.exe

When I try to sign in to Windows Live Messenger an only Windows Live
Messenger, it causes LSASS.EXE go to 100% and makes my CPU up to 75 to 85
degrees C in my laptop. I have scanned for viruses and spyware and there is
nothing. I tried reinstalling Windows Live Messenger that does not work. I
see that other people has this problem, and they have not got it fixed. It
does not do this with MSN Messenger 7.5, Windows Messenger, GAIM, or
Trillian. So please reply.

Read throught before try!

I've a workaround for this problem, which helped me in the same situation.
First of all, log off, restart your computer and login to another user
account which has administrative rights. (If your computer don’t have one,
you should first create one before restarting.)
Now you are logged in to the other Administrative acc. Go to C:\Documents
and Settings (or the same folder on your system drive) and rename your user
account folder for example like this:
Befo User
After: User.bak
Then open the user accounts control panel, and delete your user account
named: User. Delete your files too! (Of course nothing will be deleted due to
the changed folder name. ) Now go back to the first page, and create an
administrator user account named exactly the same, as your previous acc, in
my example: User. If you had a password before set exactly the same pass for
this acc!
Go back to logon screen, and logon to this acc. When all the actions are
done by the first logon procedure simply log off!
Now login again to the other Admin acc, and delete the folder named User
form C:\Documents and Settings and rename your previous folder like this:
Befo User.bak
After: User
If you set the right permissions (see below) you can leave this Admin acc,
and return to your old acc.
Now launch WLM. It will be like a new install on a new machine. You have to
type your logon and pass, set the options you want again, etc... But it’s
starts normally again, with no problem, no 100% CPU allocated by lsass.exe.

I think the goal of this procedure is setting up a new SID for your account.
SID is used for the identification of you on your computer, so after this you
will have to take the ownership of your files again, re-add permissions for
you on your files and your registry too!
Before you start the whole procedure please add permissions for
Administrators on your files and on your registry too (By default the
Administrators have the right permissions to your registry. If you not
concerned about security you can ignore the inconsistency between your new
SID and the permissions granted for your old SID on your registry, ‘cause you
can acces itt anyway, if you are an administrator.), so you will be able to
logon into your old renamed acc, ’cause you are an administrator. After this
correct your permissions for security reasons! (Remove the unknown account’s
permissions and add your’s!)

Be careful with this. You can seriously damage your account including your
documents and other data!
If you use file-system encryption may your data will be lose!
If you use Outlook or Outlook Express your passwords will be deleted, so
you’ll have to retype them! May other passwords will be deleted too!!!
I think there are 3rd party utilities to change SID. You may try to use one.

Don’t try to do this without being completely sure about what you’re about
to do!
I’m not responsible for the damages ’caused by this!
And sorry for my pour English...

Good look!