Can't trash a file or repair permissions

Hello,

I'm hoping someone can help me with this.

I have a MacBook Pro, OS 10.5.8. I recently downloaded a number of music software demo's, and after checking them out, proceeded to throw away the ones I didn't want to keep. (I used the application Find Any File to help locate all the files associated with the programs.)

One of the files couldn't be trashed – I got a message saying it was still in use. I then tried to Repair Permissions and got a message saying it couldn't be done because, "...the underlying task reported failure at exit". I shut down the Macbook, restarted, and the application was bouncing up and down on the dock. I control clicked on it and force quit. It disappeared from the dock, but I still can't repair permissions or throw away the file, because I'm getting the same messages. When I control clicked on it in the Dock, the top line, which was grayed out, said "Application Not Responding".

I thought I was being careful when I selected the files to be thrown away, and the demo that this file came from was not open when I threw away the other files, unless it was running in the background somehow. After that I ran TechTool Deluxe and it passed all the tests.

In the meantime I've purchased the music software I wanted, but don't want to install it without being able to repair permissions and start with a clean slate.

Any idea how to get rid of this thing? Any help would be greatly appreciated.