Error message at start

[Heinz]

I have windows XP. I get an error message at start of the computer, it takes a few clicks to make it go away.
The message is: Windows can not find '000000' make sure you typed the name correctly, then try again.
(Please note; the zeros are squares).
Can you help?
Heinz

[Broni]

Download HijackThis:
http://www.trendsecure.com/portal/en-US/tools/security_tools/hijackthis/download
by clicking on Download HijackThis Installer
Install, and run it.
Post HijackTHis log.