[Microsoft security essentials and Windows XP]

Yes I've tried V1.8 & V1.9 repeatedly
Results:
(1) No Update aviable! Could not be updated!
     ..definition Version: 1.291.2489.0
     Engine Version: 1.1.15800.1
(2) Definition for MSE successfully download!
     ... Version: 0.0.0.0 ...
     (guess there wasn't any download)
(3) Only Download Delta Definition for MSE
     Full Edition Definition for MSE not exist!
     First Download complete Definition for MSE perform!

Reset (RAUE) is working fine - just not very helpful

Will try on - if I'll find a clue i will report it

[Microsoft security essentials and Windows XP]

Hello sorry MSE Updater don't help to update my definitions anymore - i don't know why  last possible update is still 1.291.2489.0

I've found this Wayback Machine link from a Japan XP forum - maybe it can help you - downloadtime ~ 5 min!

http://web.archive.org/web/20190423090918/http://definitionupdates.microsoft.com/download/DefinitionUpdates/VersionedSignatures/AM/1.291.2489.0/x86/mpam-fe.exe

http://skqdju.blog.jp/archives/17114255.html