Nail.exe actually comes from a company called direct revenue. It is a kind of adware/trojan.
download, install, and update the free version of Ewido security Suite
*www.ewido.net/
download CCleaner and scrub ur pc for junkdo not run it yet.
*www.ccleaner.com/
download this installer for the Nailfix utility revised
*www.noidea.us/easyfile/file.php?download=20050711214630636
with the help of ccleaner, remove nail.exe, if it appears in the startup list.
now reboot into safe mode. and run the above utilities.
for further details click
*netrn.net/spywareblog/archives/2005/05/10/got-aurora-nailexe/
*www.spywarewarrior.com/viewtopic.php?t=14580