We were in the middle of the session last night and couldn't drop and remove the extensions. Or chose not to, at least. This morning, I've opened up the campaigns that I run and I don't have that behavior. My extensions are GURPS Core Unity, GURPS Adjustments, GURPS Audio, Shops and XP Awards. So I think it has something to do with his set up. Is there a control that needs to be toggled somewhere generically?
Also, am I correct in assuming that yours and Yako's extensions are different from each other? If so, can one of you explain the differences to me?