Generally, there are at least two approaches you can take (after satisfying yourself that malware is not involved):
a. Do a search of your system (all files and file extensions visible) for any file with eventwnd in filename.
b. Search all startup items for a prompt for said filename, using a tool like Autoruns and looking only at the Logon tab.
AutoRuns for Windows - http://technet.microsoft.com/en-us/sysinte...s/bb963902.aspx
For users comfortable with manually searching the registry...just Start/Run...type regedit, hit OK...then place cursor at top of list on left side. Then, click Edit/Find...type in filename, make sure that there checkmarks by Keys, Values, and Data...hit Find Next. If you get anything as an item or entry, delete that and then go back to Find Next and hit it again...and again...until regedit tells you that the entire registry has been searched. This will eliminate stray registry entries which might be to blame.
Users inexperienced/uncomfortable with searching the registry probably need to forego the third option.