Have actually been having a similar problem as described here. Have had a few issues since upgrading to supercache 1.0 and the latest wordpress. 1 was our feed would never get updated so I had to turn caching off there. Also we are expereincing the same issue with the Add Posts. we are a pretty high traffic site, with a lot of content. I find that if I clear the cache you can get to the Add Posts page fine, however the larger the cache grows the slower the page gets. After doing some debugging I found the function it gets hung up on is: wp_cache_post_edit(). I hope this helps.