[TYPO3] Help, my site is down!

[Darryl Krause]

Hi all,
 
I have just discovered that the non-profit site I run has been "down" for some days. I have no idea what has happened as I have not done anything in the Back End for a while.
 
The problems seem to show themselves as the TS template is parsed. Any part of the TypoScript that refers to any file (either an HTML template, an image file, a php script, etc) is unable to find the file. I am able to log into the backend and the Filelist shows all of the files as still being where they should be.
 
The installation has one major site and several subsites. I have not converted to TV yet, so the main site is still based on a TS template, which has an HTML template for the basic layout. The only thing that gets rendered for this site is the background colour, which is defined in TS. All else is dependant on the HTML template file which cannot be found.  
 
Apart from a blank page with the correct background colour, I am also able to get the AdminPanel to show...
 
Under the "TypoScript" section of the Admin Panel several errors occur under "Parse template". For example...
"fileadmin/mi_site/tmpl/printversion_content_mi.tmpl" is not a file (non-uploads/.. resource, did not exist).
..and several other error messages relating to HTML template files
 
Also under "Page generation" / "php, initialize"...
"typo3conf/ext/tt_news/pi/class.tx_ttnews.php" is not a file (non-uploads/.. resource, did not exist).
..and several similar error messages related to extensions.

There are some similar error mesages under other sections also. 
 
Trying to hit each of these files with a web browser confirms that the files are where they should be and can be read. Yet they appear to be invisible for the TypoScript parsing.
 
A couple of the subsites are based on pure TS templates, so they are able to render more. Content elements show text, but no images. The images are not even referenced in the HTML code. The Admin Panel reveals that errors occur during the rendering of the page. For example...
"uploads/pics/be_ny_liste.gif" is not a file (non-uploads/.. resource, did not exist).
 
What on earth is going on here? 
 
If I had been working on the site before the errors had occurred I could go back and check what I had done. But the last work I did on the site was entering some content more than a week ago. At that time everything was working fine.
 
That leaves me wondering if the Hosting company has changed something, but I am not sure what I can look into to check that. I would like to have a bit more to go on before contacting them so that I can back up my concerns. Can an upgrade of something on the server have caused this?
 
Any input greatly appreciated!!!
 
Regards,
-Darryl
 
Typo3 v. 4.1
PHP 5.2.4
Apache 2.0.59
MySQL 5.0.32
 
 
PS. Sorry for the HTML e-mail. I am away at the moment and only have access to a limited WebMail client.