error message c:\WINDOWS\mI3D71.dll

Go get HIJACKTHIS, run that, scan the machine and see if it's in the list. Check the box on that line and click remove or delete.

DO NOT REMOVE ANYTHING ELSE.
Bob

in fact Google shows you're the only one to have mentioned mI3D71.dll

Since this error message appears at boot up, it is likely that something was deleted but there is still a startup registry entry looking for it.

Have you run any scans recently and deleted anything suspicious? If so perhaps that had some startup file.

Have a look at the System Configuration Editor, (Start button > Run, type in msconfig and click OK). Head over to the Startup tab and look down the list for anything that suggests this. You may have to expand the column header widths to the right to see full entries.

If you find anything, remove the tick and click Apply/OK. That should get rid of the error message.

Mark