I've just noticed that one of our publishers has been adding PDFs as file assets, instead of PDF assets. It doesn't seem to affect too much though… is there some functionality we might miss out on if this continues? Can you "morph" a file asset to a PDF asset?
I think matrix uses the special pdf and word file types to identify assets of that type so the search module can pull keywords out of them.
The contents of a PDF asset are indexed, making them searchable, where the contents of normal file assets are not. The same goes for word document assets.
There is a section in the system configuration under "External Tools Configuration" which allows you to specify the path to the tools which allow pdf and word files to be indexed.
Fortunately, you can morph file assets to PDF assets 
You will have to re-index those morphed assets to generate indexing information, though.
I just tried to morph one of these assets - went to the settings screen, selected PDF, put the password in and was told only assets under contruction could be morphed. So I put the asset under construction, went back, did it again and was told I don't have permission to morph the asset (even though I'm a system admin). So, I tried to change the status back to live, but now I'm getting errors saying the asset was "not found in the repository" and the transaction was aborted. The asset needs to be live again as soon as possible. It's a form that people use every day.
In short, trying to morph was a dismal failure. This kind of stuff really tries my patience with this product. Help!
FYI, any error that affects your system functionality in this way should be reported via the Squiz Support team for immediate action by one of the support technicians. The forums are not monitored often enough to be used to report critical issues.