It started jumping around a lot...
Try typing /se mo classic
That sets the mod to classic. Just in case you have a yet another silly mod on.
Also, about not being able to upload replays:
Apparently everyone else has this problem, too.
Several people in IRC have complained about this with the same error message. I have tested this and I get it, too.
Same goes with uploading stuff on manage attachments, nobody can.
This has been tested with Internet Explorer and Mozilla Firefox... Even though I think it won't work on any other browser.