The .flac files are only supported on v1.4.1.2 or later as far as i know. Have you checked the route file whether it's trying to reference non-exissting .wav files or the .flac files?
Any Intel integrated graphics prior to the HD series found in the Core i3, i5, or i7 line of processors are known to handle openBVE poorly since these were budget graphics solutions for basic tasks and basic multimedia.
If you have a desktop, consider investing in a decent graphics card (PCI-express)