I had the same issue. I found "Plus HD" in my add/remove programs list. The sneaky bugger had created a load of Scheduled Tasks that installed the extension in browsers like Chrome and Firefox at "random intervals".
I've un-installed it and the scheduled tasks have now been removed. Hopefully that worked"
02-07-13BigChiBelly Level 2
Fantastic! Thanks. I had completely missed seeing it in the programs list. Cant tell you how many times I'd looked there. Doh!
After un-installing it and running CCleaner on the registry I hope I've removed all remnants of the bugger! Ive checked scheduled tasks too an nothing in there refers to it.
Thanks to you and caver_tim I'd thought I'd be stuck with this one.
Phew what a relief! I owe you both a drink.