Footage Skipping Ahead?!

[Full Spectrum]

Rather suddenly I am suddenly beset with the following problem in a show file that's been working reliably until just now.

Every 25 seconds, my footage jumps ahead by a few frames, as if "catching up" to the spot it should be. It's minor, but very noticeable on slow smooth footage. I'm using timeline mode.

Anyone have any ideas? Rather urgent I get this fixed ASAP...

Thanks

[Full Spectrum]

Additional information:

Resolume 5, DXV 3 codec used, 2500x1600, 7 layers.

The only thing that I changed is adding three more clips to what's already a massive deck. Could three clips have been the straw that broke the camel's back? Could quantity of clips be the problem?

Thanks again

[drazkers]

What happens with a new composition with half the files?

[Zoltán]

are you sure there is no SMPTE involved?
OSC/MIDI in/output loop?