As I stated before "could be a bad boot media and you can try to re-install, make sure to save the settings and config at Maint. > Misc." or you can test with the DSS on a USB Flash Stick and boot with this and see if it is viewable.
The Quota.log file can be downloaded from the GUI in STATUS -> Hardware -> Function: Logs.
Did you try to stop and restrat the Apache from the Console screen by entering CTRL ALT T then select "addons" then select Apache then stop and restart?
You can also submit a support ticket from your User Portal and send in the log file to our support team for us to review them as well.
Such system behavior could be related to an issue with the storage disk(s) or the RAID controller itself. Try to check the controller health and storage disks health too.