Cannot delete .plist files - The parameter is incorrect

Hi.  I administer a network of PCs and Macs.  I need to delete a bunch of .plist files generated by the macs, but whenever I try I get

"Error 0x80070057: The parameter is incorrect".  I have attempted using dos and powershell and get a response telling me the files do not exist, even though a dir shows they do.

I am running Windows Server 2008 R2 and unable to attempt to use a mac to delete them.

Any ideas would be good. Thanks