Yes, via FTP (Filezilla). But why would only the forum attachments have been downloaded incorrectly? All other files (inc. e.g. Joomla files) were downloaded fine. And how do I check if the problem was the download from the old host or the upload to the new host, since the files are scrambled and I can't see them?
I guess I should just try downloading and reuploading them?
You think this issue has nothing to do with the database? Perhaps with an encryption key or something?
I chose GoDaddy because they still allow PHP 5.4. DreamHost removed it from their hosting environment and messed up my site, and I am not at a point in my life right now where I can invest the time to solve the multitude of errors this forced move to PHP 5.5 created. I guess I should look for another host that offers PHP 5.4 and move the site there. If you can recommend some I would appreciate it.
Thanks for your quick reply. At least now I have an idea of what the problem might be.