Latest Windows Defender Update Failing - Anyone Else?

[#1]

I've tried several times (both through Automatic Updates and Windows Update) but failed to install the latest signature update for Windows Defender - Definition Update for Windows Defender - KB915597 (Definition 1.35.716.0)
I'm getting the following entries in the event log:
System Log
Windows Defender has encountered an error trying to update the engine.
New Engine Version: 1.1.3604.0
Previous Engine Version: 1.1.3604.0
Update Source: User
User: **********\Owner
Error Code: 0x80508007
Error description: Your computer is low on memory. Close some programs and try again, or search Help and Support for information about preventing low memory problems.
[It seems unlikely that my system is short of memory]
Application Log
EventType mptelemetry, P1 80508007, P2 updatedefinitions, P3 unspecified, P4 1.1.2960.0, P5 mpsigstub.exe, P6 1.1.1593.0, P7 windows defender, P8 NIL, P9 NIL, P10 NIL.
I'm running XP SP3.
Is anyone else seeing this or any suggestions?
Thanks - Bob

[#2]

I've just updated my version to Definition 1.35.716.0 and its worked without a problem, albeit on another Windows OS
Have you tried shutting down your PC, restarting then attempting the update again, afterall that fixes a lot of MS issues 

[#3]

Thanks for the quick response James.
Yes, I've tried rebooting but still get the same errors.
Bob

[#4]

Uninstall & reinstall?
It only takes a couple of minutes for Defender on XP......
(& maybe do a registry cleanup before the install)

[#5]

I think I'll wait for the next signature update and see if that works. If not I'll try reinstalling.
Bob

[#6]

I've just had 1.37.1.0 fail to install after automatic download.  However, when I manually updated using the help menu it worked ok. Huh? (I cleaned my registry on Tuesday, but I can't see why that would affect it one way or the other...?)

[#7]

I've just updated successfully with 1.37.1.0 so I guess it was a problem with the previous version. Googling "1.35.716.0 failure" now returns a few hits so it looks like I wasn't the only one having problems.
Bob