And make sure you are in the correct directory. Windows will not report that "c:\blahblah\something(2).dll" is invalid if "something(2).dll" doesn't even exist in "c:\blahblah"...
Also, (although this shouldn't be the case, but if it is, there is certainly something wrong with your setup), make sure that files aren't hidden:
Open Windows Explorer (Start > Run > explorer.exe) and make sure you can view all hidden and system files:
Tools menu > Folder Options item > View tab > Advanced Settings list > Hidden files and folders > enable "Show hidden files and folders" and disable "Hide extensions for known file types".
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