well,
Type "Sysedit" (without the quotes) into the run command in the Start Menu. This opens up the System Editor. In WIN.INI and SYSTEM.INI, look for references to the offending vxd (use the search function). If you find it referenced, put a "REM" plus a space in front of it (w/out the quotes). I'd recommend backing these two (plain text) files up before making any permanent changes. Save if changes are made. Reboot to see if the error message disappears.
basically, it seems like that vxd error isn't causing any harm , right? It's just annoying
the BEST way would be to figure out what he uninstalled , if anything, recently and to re-install it again, which should replace the vxd. else, you could alway search the registry for it, but that is a last resort