Fixing ASP websites

General information for the business: Charity websites
Kind of development: Customization of existing program
Description of requirements/functionality: ASP websites not working properly after changing the server
Specific technologies required: ASP
Extra notes: We have a few websites - 3 or 4 running XCITEcms. It seems to have been made using ASP.
The server on which they were, was upgraded and there are some problems:
- All the cms's are not working - when I save the edited files I get the error : [HttpRequestValidationException (0x80004005): A potentially dangerous Request.Form value was detected from the client (PageText="<p style="color:#000...").]
- at least one of the websites has some redirection or something, after the server change, the pictures are not shown

It doesn't seem to be something complicated but we no longer have an ASP developer here.

I can provide FTP access to the websites