Error in webshop: class xxxx not found

[saveshoppers]

I have this error since yesterday:

Fatal error: Class 'Varien_Data_Collection_Db' not found in /home/singlesuit/domains/singlesuits.at/public_html/app/code/core/Mage/Core/Model/Resource/Db/Collection/Abstract.php on line 36

I have not changed anything in the webshop. Also I have uploaded the directory "app" again and cleared the cache, no result. Is there someone who can solve this?

[Brent W Peterson]

Have you checked that your server has not run out of space? Have you cleared your cache folder completely?

If you have not done anything (Like changed any code) then I would suspect that something in your database changed or your hosting provider changed something

What version of Magento are you using?