For several days in a row (4-5 days) the site is not accessible - internal server error. Is this the end?

I don't think so. The site is accessible to me and I just played the hourly free roll and that is working fine.
You should try accessing the site again but it's certainly not the end, atleast yet.
Yes, it was down for several days but now, the site is back online. We don't know what happened with the site but many members hope there are no serious errors.
I visit the site without any problem now and use the free roll for some hours ago and nothing errors. I have even got emails from them about the free roll since yesterday. This day I got 1 email giving me 1 free spin.