I am having this problem too. The web panel was working fine(but slow) before. Just now, I want to create a new volume. Usually, it takes a few seconds to create the volume, but this time it hang there even after 10 minutes. Since I can't do anything, I just left that page. Now, the web panel is completely blank. I've tested on different computers and browsers. I still can ping the web panel IP though.

I am using 6.0up85.8601.5794 64bit, the OS is installed on a decent hardware

Memory (RAM) info
used Used memory (MB): 2396.68
cache System cache (MB): 45651.73
free Physical free memory (MB): 239.56