Server Error In Application???

Ok so I'm currently working on a site that has some areas in PHP and some in ASPX... I'm familiar with PHP but ASP wouldn't have a clue, anyway had to upgrade the server on the host side of things to a higher version of PHP... Anyway they did this and said they needed to move to a new server, everything seemed fine and all the PHP pages are running perfectly, however tried to login to one of the ASPX pages today and received a massive error (screen grab attached), am waiting to hear back as to what the issues is from the host, but as everyone here seems to know alot thought I'd see if anyone knew what the problem was...

I'm hoping the answer will be it's the hosts fault and they can fix it, I really don't want to have to edit ASP pages ARGH! :(

Thanks all in advance!