As I have played with, but not actually deployed, CMSMS, this thread is indeed very worrisome.
However, my tilt would be toward the cause being some "ISP Event."
The reply from them
I am not sure how much I can help with this, as we really do not support CSM, however I am more then willing to give you my input. As far as anything we have placed on the server itself that may have caused this, I am not really seeing anything that stands out. What is on the server itself is very standard services that all web-servers would hold. being MySQL, apache and PHP. are there perhaps particular versions of these services (MySQL,PHP and apache) that your CSM script requires?
Suggests that the ISP (or, at least, whoever replied to your question) was pretty clueless.
The question should have been, and the reply should have addressed... "HAVE YOU RECENTLY CHANGED ANY CONFIGURATION(S) at your end? Everything was working until (date___). I changed nothing, but now when I try to access (URL), all I get is a blank page."
It is not a matter of what the ISP has "put on the server." The question to the ISP is: WHAT HAVE YOU CHANGED BETWEEN DATE X AND DATE Y ??"
Meanwhile... if I recall correctly, the original author at one point wrote that the database was intact, and that the database checked "OK." Deleting the CMSMS files in their directories, reinstalling, then restoring the Database information, resulted in the site showing briefly, then disappearing again. (!?) [Correct me if I'm mistaken on that.]
Now, what the heck would THAT mean??
This all smells of a Server/ISP problem (ERROR!) to me.
And... WHAT might / could cause cmsms to serve page where there is nothing between the body tags??
As to The Future: I have seen many many messages where Poster A writes "check your log files." and Poster B replies "huh?" (or the request is to run php info, or... well, some other esoteric geeky thing.)
HEY DEVELOPERS! Are you seeing a pattern here?
At least, put a BIG RED WARNING FLAG somewhere at the "beginning" of things: "If you don't know what this, and this, and this, and this, and this, and this, are.... proceed at your own risk."
"To learn more about [fill in the blank], go here."
NEXT, more diagnostics saved somewhere. If the ISP (or a hacker) "did" something to a site, make it easier to follow the trail.
Take into account that, OF COURSE, the site is (most likely) being run on a shared server!
Keep Going!
eo