Hi Jason, let me address question by question:
Are you using the Yahoo web interface? Yes
What browser are you using? Safari Version 6.0.2 (8536.26.17)
Have you tried a different browser? Not in the same MacBook Air, I tried to send the same file, from a PC Sony Vaio and the file was successfuly sent.
If so, which and what version of that browser? I used/tired Browser Mozilla and Explorer
What is the exact text of the error message?
There was a problem!
Invalid file specified. Please try again.
The file you're trying to upload, what is the type of file? I tried to send .xls, .pdf, .gif, etc non can be sent
Is it compressed, zipped or in some sort of archived state? Not at all, simple small files
What about Yahoo? Have you tried reaching out to their support seeing you're experiencing an issue with their web interface? I have not tried with Yahoo, once the files can be sent from other PC's Laptops
Hope this helps Jason,
Cheers
NGM-