problem with saving in Tiddlywiki Classic

[Ben John]

Hi -

can somebody please let me know why I'm getting the the following message every time I try to save a Tiddler in Tiddlywiki classic.

[Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIFileOutputStream.init]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: chrome://tiddlyfox/content/overlay.js :: TiddlyFox.saveFile :: line 98"  data: no]

Also every time I have saved  to my specified folder on my hard drive, before this error message reared its ugly head, a copy  is added to a an ever growing number of copies. So am I right in assuming that each edit on a Tiddler is treated as a separate file rather than overwriting the previous one and thereby reducing the need to peer at a long list of redundant ( out of date) files.

thanks

Ben