Bizarre error

Hey guys,

I have recently ran into the oddest error I have ever seen and its got me stumped, I think I may be losing it.

I created a site, 40 odd pages, no problems everything running fine. I started to input the content to the pages (now this only happened on one page), when I copied the information across and tried to update or preview the page I got an error message, page not found (the 404 page). Thinking it was a problem with the page I deleted and created it again, still the same problem. After investigating, I was able to save any else I copied into the page just not the original content for the page (this was all normal text, no code, nothing complex, just text) I ended up able to copy it in section by section until I narrowed it down to one line. If I left it out it saved/worked no problem if it put it in I got an error and it wouldn’t save.

I don’t know what the problem is, it’s just a normal line of text and it screws the entire page.

Any ideas????