Problems while UAC is active

Can anyone help please?

I was having endless problems getting my Pinnacle Studio 11.1 to see my
camcorder. (The camcorder was seen by other software, i.e. Windows Movie
Maker and Nero on the same PC). I am also having trouble with MS Office
2000, particularly Word and Publisher. Word takes an eternity to open, I'm
talking in excess of 5 minutes but will save okay. Publisher opens straight
away but takes about 5 minutes to save a small one page item.
I turned off UAC and all these problems disappeared but I turned it back on
when I got a trojan which, fortunately, AVG picked up.
I don't mind clicking that I give something permission to start but this is
beyond a joke.
I'm the only user of this PC by the way.

Thanks in advance.