major problem with style manager main css

[CP,]

Hi i have been using vb for over a year now, coming to two years. We always make changes to our forum template.

We recently had an event and i was able to change the css in Style Manager > My Custom Skin > Main CSS

We last changed the main css section a week or two ago and now i am trying to modify something and save the whole maincss. But it dosent save and gives me a page cannot be found whenever i press save?

I have tried other styles that i have and i have the same problem with all the skins.. only in the "Main CSS" section through Style Manager > My Custom Skin > Main CSS each time i press save i get a page cannot be found. Ive tried on IE and FF and i encounter the same problem.

I really dont know what is wrong? Cheers.