My b2evolution Version: Not Entered

I uploaded b2evolution 2.4.2 to a subdomain of a new site so I could test out the new features but when I tried to invoke the install script I am presented with this:

"The server encountered an unexpected condition which prevented it from fulfilling the request.
The script had an error or it did not produce any output. If there was an error, you should be able to see it in the error log."

What I cannot tell is if this is a b2evo error or if it's something else. My host has php5 and mysql 5 and are telling me this doesn't look a problem on their end (but they all say that don't they?).

So, anyone seen this before or know how to fix it?