Antivirus Stops Scanning Everytime a Virus is Found

Twice I have tried to run your anti-virus program overnight, only to find that when it finds a particular file, it waits for me to designate where to place it. How can I continue to scan and let me decide these things after the scan.

Avast 4.6, Win XP Professional, 1.5 Pentium 4 Processor

See this post, please.