Hi Rob, welcome to the Sony Forums 
There's no restriction with PC-generated filenames as such, only that they dont exceed the accepted length and character set and aren't buried deep in a file subdirectory.
Make sure the images are in a top-level folder. Also make sure you have jpegs or tiffs, and that your filename is less than 10 characters long; ideally eight, in the form of IMAG1234.jpg
Let me know how you get on 
Cheers
Mick