> No, definitely UAC this time. I've been using Defender for ages without UAC
> on, no problem (but I did just check Defender to make sure ;-)). When I
> activate UAC it blocks 2 progs at startup - I can manually allow them each
> time, but it's a pain...

Apologies if this shows up twice (the web interface is not very good).

Are these programs in a logon script? That is the only instance where UAC
actually "blocks" something; or are you using the term "block" to mean
"prompt to allow" in this scenario?