problem "explorasi.exe not found"

hello everyone
I removed the brontok-a trojan on my computer using avast, when I open the computer, a window pops-up saying it couldn’t find the file explorasi.exe??? I remember it was already deleted by the anti-virus since it was infected by the brontok trojan. And when i try to run regedit, it say’s that the administrator disabled regedit. i’m still using avast for the computers.
could u pls make some suggestions how could i access the regedit and get rid of this message.

This tool may help

http://www.symantec.com/security_response/writeup.jsp?docid=2004-050614-0532-99

Probably best to use hijackthis rather than directly editing the registry. Its safer and we can look for other entries that may be present

http://www.bleepingcomputer.com/files/hijackthis.php

Just extract the program to its own folder (C:\hijackthis), generate and post a log. Don’t fix anything yet.

Google is your friend…
http://windowsxp.mvps.org/ToolsQuit.htm
http://www.techspot.com/vb/topic18481.html