Help Where do Invalid Files go?

[3characters]

I attempted to download an app and it appeared to have installed fine. It was even OKed by Lookout so I would think it is somewhere on the phone. I got the usual Low Memory Storage warning. I also got an Invalid File warning and the app appears no where on the phone. I could care less about this particular app, just thought it would be fun to check out. (It's some silly spider game).
Is there somewhere on my phone that the file is taking up space that I can go and erase it? Is there a folder or something for incomplete downloads that can be purged as well?

 

[trenchkato]

Look in /cache if it is not in there as download-1.Apk then I on't believe that it is on the phone

 

[3characters]

Where do I find /cache?

Smartphones are new to me. If there isn't an obvious app or file I won't know where to look :/