SEP client install fails

What os are you running? I actually just had this happened when I upgraded to windows 7. For me it seemed that a roboot didn't help but I didn't realize that Windows 7 was installing updates in the background. Since I only tried the roboot once and the updates continued after I rebooted it appeared that the reboot didn't help. In fact it did and once all of my updates where done installing the SEP install worked no problem. So you should check if windows updates are going on. If they are not I guess I would have to ask if you have had any failed installs recently. For instance you were installing iTunes and it failed half way or you shut down before that install was done?

Grant-

You many try this.
Open your registry, take a backup of the registry first.

no do a control+F  search for pendingfile

You will get atleast 5 keys , delete all of them.

do a system reboot

Now try to install should work fine.

Is actually a hook from MSI in the registry.  Something was installed (or uninstalled) with MSI and it probably didn't go as planned.

The MSI actually writes data into the pendingfilerename key to indicate that something needs to happen upon reboot.  Before it begins the install, MSI will check for this key, and, if found with data, will exit the "new" run of MSI, as there is something that needs done before another MSI can be run.

Removing the data from this key SHOULD allow another MSI to run (if not, try rebooting after removing it), but it's working around a potentially damaged install of some other software (which could even be SEP).  Think back...what was the last software you installed?  Is it working correctly?

You can also try using the MSI Cleanup Utility to try removing entries from the MSI catalog...although here I'm not sure how helpful it'd be.

(The MSICUU doesn't uninstall software, as is sometimes thought...it merely removes the reference to the software from the MSI catalog, thus allowing you to reinstall over the top, since MSI doesn't know the software exists after removing the entry from the catalog)

Pending File RenameOpearations is a value of Session Manager.
FileRenameOperations is a folder below session manager.

Highlight Session Manager then look at the value on the right hand side and not below Session Manager you should find PendingFileRenameOperations.