What’s the extension of the file ? Anyway, I’m sure you can just erase it. It’s inside Windows/temporary folder. I have Windows/Temp/avast4 folder as well, but it’s completely empty…

EDIT: However, there is information from the first hand, from one of Alwil experts, PK. While I was editing this post, he already gave you an answer…

So, you’re clear to erase that file without any after effects.

Cheers !