I am still in the trial period of using mIRC so please let me know if this is my issue.

I recently loaded mIRC and Invision on my Vista box. When I access a link from a site such as packetnews, I get the following error: Windows cannot find 'irc://.....'. Make sure you typed the name correctly, and then try again.

I saw a post for this before, but was unable to find it again. Maybe it was on the Invision site.
I am running 6.21 with Invision 3515b