If you're using IE 8, you'll have a problem. With IE 7, and Vista, you have to run IE "As Administrator", and/or play with the UAC to get it to work.
But, MyHouse is flaky anyhow. I hardly ever even try it anymore. I use LogMeIn (free) and it gives me full remote control of the PC - just like you're sitting there. (The video is a tad better with MyHouse, but LogMeIn is acceptable)
And if you're blocked from the LogMeIn.com site, get the LogMeIn Ignition application and run it from a thumb drive. Searching for coupons should result in being able to get the Ignition licence for $19.95/yr. and it's way worth it!.