So look at the line, and there are two possible parts:
Directories.OLD_DATAFOLDER
Which looks like an enum, but we can't see it. If it's an enum then its won't be that.
new IniFile(...);
Which means it's in the constructor, which we can't see. You've got a cross threading error in code we can't see which probably shouldn't be using threads and the fragment you show use doesn't use threading anyway. That doesn't exactly make it easy for us to work out what your problem might be...:laugh:
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
